Download Mechanics:

Level 2 Physics
Relevant past NCEA Exam questions for 91171
Mechanics:
Relationships (taken directly from the Achievement standard 91171:
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NZQA Exams, compiled by J Harris
[email protected]
Achievement Standard
Subject Reference
Physics 2.4
Title
Demonstrate understanding of mechanics
Level
2
Subfield
Science
Domain
Physics
Credits
6
Assessment
External
Status
Registered
Status date
17 November 2011
Planned review date
31 December 2014
Date version published
17 November 2011
This achievement standard involves demonstrating understanding of mechanics.
Achievement Criteria
Achievement
Achievement with Merit
Achievement with Excellence
 Demonstrate
understanding of
mechanics.
 Demonstrate in-depth
understanding of
mechanics.
 Demonstrate comprehensive
understanding of mechanics.
Explanatory Notes
This achievement standard is derived from The New Zealand Curriculum, Learning Media,
Ministry of Education, 2007, Level 7; and is…..
1
Assessment is limited to a selection from the following:
Motion:
 constant acceleration in a straight line
 free fall under gravity
 projectile motion
 circular motion (constant speed with one force only providing centripetal force).
Force:
 force components
 vector addition of forces
 unbalanced force and acceleration
 equilibrium (balanced forces and torques)
 centripetal force
 force and extension of a spring.
Momentum and Energy:
 momentum
P a g ein momentum in one dimension and impulse
 2 |change
 impulse and force
 conservation of momentum in one dimension
 work
 power and conservation of energy
 elastic potential energy.
NCEA 2012 Sample paper
QUESTION ONE: MOTION (NCEA SAMPLE PAPER 2012)
(a)
Jason drops a stone vertically down from the top of a bridge into the water below. It
takes 2.5 s for the stone to reach the water.
Calculate the velocity of the stone when it hits the water. Use g = 9.8 m s–2. [A4]
(b)
Explain the forces acting on the stone as it falls towards the water below. [M6]
(c)
Explain in detail how the forces that act on the stone change as it enters the water and
sinks down to the bottom of the river bed. In your answer, you should include an
explanation of how this would affect the motion of the stone. [E8]
(d)
On another occasion, Jason throws the stone from the ground at an angle of 34 to the
horizontal with a velocity of
25 m s–1 as shown in the
diagram.
Determine the range by
calculating:
 the velocity vector
components
 the time taken to
reach maximum
height. [E8]
QUESTION TWO: FORCES (NCEA SAMPLE PAPER 2012)
Jason’s dad Mike drives his car at a constant
speed around a horizontal circular track as
shown in the diagram below.
(a) The radius of the circular track is 28.0 m.
Mike drives at a constant speed. It takes
12.0 s to go around the circular track
once.
Calculate the speed and hence the
acceleration of the car.
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(b)
Explain why the motion of the car
would be affected if there was an oil
patch on the circular path as shown in
the diagram below. (Assume that the
oil causes complete loss of friction
between the car wheels and the surface
of the track.)
In your answer, you should include:
 an explanation of the forces acting
on the car while it is moving in a circle
 an explanation of the how the
motion of the car is affected once it encounters the oil patch. [E8]
(c)
On another occasion, Mike drives his car over a uniform bridge. The bridge has two
supports. The mass of the bridge is 5000 kg and the mass of Mike and his car is 1500
kg. The bridge is 30.0 m long. See the diagram below.
Calculate the support provided by end A and end B of the bridge when Mike and his car
are at a distance of 10.0 m from end A of the bridge. In your answer, you should
include arrows to show:
 the weight of the bridge and the weight of the car
 the support forces provided at the ends of the bridge. [E8]
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QUESTION THREE: MOMENTUM AND ENERGY (NCEA Sample paper 2012)
(a)
Mike’s car collides with a stationary trolley as shown in the diagram below. After the
collision, the car and trolley lock together and move as one. Calculate the final velocity
of the car and trolley together. [M6]
Mass of Mike’s car = 1500 kg
Mass of trolley = 650 kg
Initial velocity of Mike’s car = 18 m s–1
(b)
Mike’s car has a long crumple zone.
Explain in detail why having this crumple zone would make a difference during impact.
In your answer, you should include ideas of velocity before and after the impact. [E8]
(c)
Mike’s car is towed away by a tow truck. The rope attached to the car makes an angle
of 42 with the horizontal. The rope pulls the car with a force of 850 N. The car moves
a distance of 45 m along the horizontal road during a time of 15 s. See diagram below.
Calculate:
a. the work done by the tow truck on the car.
b. the power produced by the tow truck while it is moving the car. [E8]
(d)
Suspension is the term given collectively to the springs, shock absorbers, and linkages
in a car. The suspension springs on Mike’s car are soft springs when compared to the
suspension springs of a truck.
Explain in detail why, in terms of spring constant and extension, a truck needs to have
stiffer suspension springs. [E8]
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Section 1 Motion:
KNOW THE EQUATIONS (Motion, kinematics & projectiles):
Symbol’s complete name
And SI unit
Situation where equation is most
commonly used (or notes about this
equation). Use your own paper
v
v
Δd
Δt
Δd
Δt
a
v
a
t
Δv
v f  vi  at
vf
d  vi t  1 2 at 2
vi
d
vi  v f
2
a
t
t
v f  vi  2ad
2
2
d
QUESTION FOUR: THE HIGH JUMP (NCEA 2010, Q3)
Lucy is competing in a high jump event. She runs up to the bar, jumps over it and lands on
the mat.
(a)
She starts her run-up by accelerating from rest at 2.21 m s–2 for 2.0 s. Calculate the
distance she travels in this time. Write your answer to the correct number of
significant figures. Explain why you have used this number of significant figures.[A]
QUESTION FIVE: TRAVELLING BY CAR (NCEA 2005 Q1)
(a) A car starts from rest at traffic lights and accelerates in a
straight line to a speed of 50.0 km h–1 in 10 seconds. Using
the approximation that 50.0 km h–1 = 13.9 m s–1, show that the
car’s acceleration is 1.4 m s–2. [A]
(b) The mass of the car and its occupants is 1357 kg. Calculate the
net force acting on the car when it is accelerating. [A]
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(c) State whether the force that you calculated in your answer to (b) is equal to, less than or
greater than the total driving force provided by the car’s engine. [A]
(d) Explain clearly the reason for your answer to part (c). [M]
(e) Calculate the car’s power output during the first 10 seconds of its motion. Give the
correct unit for your answer. [E]
QUESTION SIX: THE BIKE RIDE (NCEA 2011 Q1)
(a) Jacquie is a bike rider. One morning she starts riding from rest and
accelerates at 1.2 m s–2 for 14 seconds. Show that her final velocity
after 14 seconds is 16.8 ms-1. [A]
(b) Jacquie then rides along a horizontal circular path at constant speed.
Describe what it is that provides the force needed to keep the bike going in a circle. State
the direction of this force. [M]
QUESTION SEVEN: THE AIRCRAFT (NCEA 2007 Q1)
An aircraft is flying at a height of 600 m above the ground.
(a)
Explain why the aircraft flying is not an example of
projectile motion. [M]
(b)
While the aircraft is flying horizontally at a speed of 35 m s–1, a packet is dropped
from it. Calculate the speed of the packet when it reaches the ground (include a vector
diagram). [E]
(e)
While landing, the speed of the aircraft reduces from 80.0 m s–1 to 25.0 m s–1 in 8.0
seconds. Calculate the size and direction of the acceleration. Express your answer to
the correct number of significant figures. [M]
QUESTION EIGHT: The basketball throw (NCEA 2009, Q2)
Jordan then throws the basketball horizontally,
with an initial horizontal velocity of 7.8 m s–1, at a
height of 1.4 m from the floor.
(a) Calculate the velocity (magnitude and
direction) of the ball just before it hits the
floor. [E]
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1.4m
QUESTION NINE: ROWING (NCEA 2006 Q1)
Steve is in a rowing race. The total mass of Steve and his
boat is 120 kg
(a)
At the beginning of the race, he is at rest. When the
race starts, he accelerates to a speed of 4.5 m s–1 in 5.00 s. Calculate his acceleration.
Write your answer to the correct number of significant figures. [A]
(b)
Calculate the distance Steve travels in the first 5.00 s. [A]
(c)
Calculate the minimum average power Steve must produce to cause this acceleration.
Write your answer with the correct unit. [E]
(d)
Explain clearly why the average power Steve must actually produce will be greater
than that which you calculated in (c). [E]
(e)
Later in the race, the boat is moving at constant velocity. Determine the size of the net
(or total) force acting on the boat. [A]
QUESTION TEN: THROWING THE DISCUS (NCEA 2010, Q1)
James is preparing to throw a discus by swinging it in a horizontal
circle. The diagram to the right shows the path of the discus moving
clockwise as seen from above.
(a)
Draw two labelled arrows on the diagram above to show the
velocity and acceleration of the discus at the instant shown. [A]
(b)
James releases the discus at the position shown in the diagram
below. Draw an arrow showing the direction the discus travels.
Explain why the discus then travels in the direction you have
drawn. [E]
(c)
Before throwing the discus, James swings it round in a horizontal
circle at a constant speed of 11 m s–1. The mass of the discus is 2.1
kg, and at one time he applies a horizontal force of 290 N to it.
Calculate the radius of the discus’s circular path. [M]
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James releases the discus at an angle of 37° to the horizontal.
(d)
(e)
Describe the energy changes as it rises, falls, lands and rolls, coming to a stop.
You may ignore any forces caused by the air. [E]
State the size and direction of the acceleration of the discus at the highest point of
its trajectory. [A]
(f)
It takes 2.4 s to return to the height at which it was released, as shown in the diagram
below. (James releases the discus at an angle of 37° to the horizontal.) Calculate the
speed at which he releases the discus. [E]
(g)
In fact there is a vertical force acting upward on the discus called lift. Explain how
this lift force would affect the horizontal distance travelled by the discus. [E]
QUESTION ELEVEN: PROJECTILE MOTION (NCEA 2006 Q3)
Marama is a long-jumper. She runs down a track, and jumps as far as
she can horizontally. Her take-off velocity is shown in the diagram
below. You can assume there is no air resistance. Acceleration due
to gravity = 9.8 m s–2.
(a)
Show that the horizontal component of her initial velocity is 6.0 m s–1. [A]
(b)
Show that the vertical component of her initial velocity is 2.2 m s–1. [A]
(c)
Calculate the distance she jumps horizontally. [E]
(d)
State the size and direction of her acceleration at the highest point. [A]
(e)
Explain why the horizontal component of her velocity is constant. [M]
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QUESTION TWELVE: TRAVELLING IN A HOT AIR BALLOON (NCEA 2005, Q3)
A hot air balloon is hovering in a stationary position, 320 m above the
sea. One of the passengers throws a tennis ball with a speed of 25 m s–1
in a horizontal direction as shown in the diagram below.
(a)
Assuming that it was a calm day with no wind, calculate the
horizontal distance d from the balloon to where the ball lands in
the sea. [M]
QUESTION THIRTEEN: THE SOCCER KICK (NCEA 2011, Q3)
(a)
Ernie’s son Jacob kicks a ball towards Ernie in the garden. Ernie is 1.75 m tall. Jacob
kicks the ball with a velocity of 24 m s–1 at an angle of 36° to the ground. Jacob is
standing 35 m away from Ernie.
Will the ball hit Ernie or go over his head? In your calculations, start by showing that
the horizontal component of the initial velocity of the ball is 19.4 m s–1. [E]
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Section 2 Force:
KNOW THE EQUATIONS (Forces, Springs & Circles):
Symbol’s complete
name And SI unit
Situation where equation is most commonly
used (or notes about this equation).
Use your own paper
F
F = - kx
1
k
x
F  mg
m
2
g
Ep  12 kx2
EP
3
Δ E p = mgΔ h
Δ Ep
4
h
Fc 
mv 2
r
FC
5
m
v
r
ac 
v2
r
ac
6
v
r
v
2r
T
T
7
v
r
f 
1
T
f
T

  Fd
F
d
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8
9
QUESTION FOURTEEN: TRAVELLING IN A HOT AIR BALLOON
(NCEA 2005, Q3)
A hot air balloon is rising vertically at a constant speed of 2.5 m s–1.
(a)
Compare the sizes of the total upward force acting on the hot air balloon
with the total downward force acting on it, giving your reasons. [M]
QUESTION FIFTEEN: ERNIE’S MOWER (NCEA 2011, Q3)
(a)
Ernie is pushing a lawn mower with a force of 26 N at an angle of 34° to
the ground, as shown below. Explain fully why not all of the 26 N force
exerted by Ernie is used to push the lawn mower horizontally along the
ground. [M]
26N
34°
(b)
Calculate the power produced by Ernie when he accelerates the mower through a
distance of 4.0 m in 3.0 seconds. Give the correct units for your answer.[M]
QUESTION SIXTEEN: AT THE AIRPORT (NCEA 2007 Q2)
Some painters are working at the airport. They have a uniform plank resting on two supports.
The plank is 4.0 m long. It has a mass of 22 kg. The two legs that support the plank are 0.50
m from either end, as shown in the figure below.
(a) The plank is in equilibrium. Draw labeled arrows of appropriate sizes in the correct
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position showing the forces acting on the plank on the diagram above. [M]
(b) Calculate the support force on the plank at A if a painter of mass 60 kg sits 0.75 m
from A, and another painter of mass 75 kg sits at a distance of 0.80 m from B. Use g =
10 m s–2. [E]
QUESTION SEVENTEEN: ROWING (NCEA 2006 Q1)
The diagram below shows part of the side of the boat and one of Steve’s oars as seen from
above. The oar pivots on the side of the boat. The oar is 4.0 m long. Steve’s hand is 0.50 m
from the pivot. During a warm-up, Steve exerts a force of 450 N on the oar as shown in the
diagram below.
(a) Calculate the size of the force that the oar exerts on the water. [M]
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QUESTION EIGHTEEN: THE BRIDGE (NCEA 2011, Q2)
Jacquie cycles along a uniform bridge that is supported at both ends, as shown in the
diagram.
(a)
The length of the bridge is 25.0 m. The mass of Jacquie and her bike is 72 kg. The mass
of the bridge is 760 kg.
Calculate the support force (FA) provided by end A and the support force (FB)
provided by end B of the bridge when Jacquie is 5.0 m from end A. [E]
(b)
Express your answers to part (a) to the correct number of significant figures. Give a
reason for your choice of significant figures in your answers to part (a). [M]
QUESTION NINETEEN: THE CAFETERIA TRAY (NCEA 2009 Q3)
Harry carries his tray of food to his cafeteria table for lunch. The uniform tray is
0.500 m long and has a mass of 0.20 kg. It holds a 0.40
kg plate of food where the centre of the plate is 0.200 m
from the right hand edge. Harry holds the tray on the lefthand side with one hand, using his thumb as the pivot
(fulcrum), and pushes up 0.100 m from the pivot (fulcrum)
with his fingertips.
(a)
(b)
State the conditions necessary for the tray to be in equilibrium. [M]
Calculate the weight (force of gravity) on: [A]
(i) The plate of food
(ii) The tray
(c)
Calculate the size of the upward force that Harry’s fingertips must exert to keep
the tray level. [M]
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QUESTION TWENTY: CIRCULAR MOTION (NCEA 2006 Q2)
Jan is competing in a
hammer-throw event. This
event involves swinging a
10 kg iron ball attached to a
steel wire in a horizontal
circle.
The diagrams below show
Jan and the hammer from
above.
Diagram 1
(a)
On Diagram 1, draw an arrow showing the direction of the iron
ball’s acceleration. Label it “a”. [A]
(b)
On Diagram 2, draw an arrow showing the direction of the force
the steel wire exerts on Jan. Label it “F”. [A]
(c)
Explain why a horizontal force is needed on the ball, even
though it is moving at constant speed. [E]
Diagram 2
The ball rotates in a horizontal circle of radius 2.0 m. The time for
one rotation is 1.5 s. The iron ball’s mass is 10 kg. The circumference of a circle is: C = 2πr.
(d)
Calculate the size of the centripetal force acting on the iron ball. [E]
(e)
After a few rotations, the ball has the same radius of rotation, but a shorter period.
Explain what effect this will have on the horizontal force acting on Jan. [E]
QUESTION TWENTY ONE: THE BAGGAGE SECTION (NCEA 2007, Q3)
The baggage at the airport is delivered on a horizontal
circular conveyor belt that is moving at constant speed. The
radius of the circular belt is 7.0 m.
(a) Draw an arrow in the diagram below to show the
direction of the velocity of the suitcase that is on
the moving circular belt. [A]
(b) Explain why the motion of the suitcase on the belt
that is moving in a circle at constant speed is
accelerated motion. [E]
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(c) Calculate the time it takes for the belt to complete one rotation if the unbalanced
force on the suitcase is 5.5 N. The mass of the suitcase is 18 kg. [E]
(d) The suitcase is on wheels. The
owner pulls it across the floor
with a strap as shown in the
diagram below. The force
applied to pull the suitcase is 25
N and the strap is at an angle of
Calculate the work done
pulling the suitcase 0.80 m
along the floor. [M]
The suitcase is put on trolley A. The total
mass of trolley A and the suitcase is 33 kg.
Trolley A with the suitcase is moving with
a speed of 3.6 m s–1 when it collides
inelastically with trolley B moving in the
same direction with a speed of 2.0 m s–1.
The total mass of trolley B and its suitcase
is 35 kg. After the collision, trolley A is
moving with a speed of 2.4 m s–1 in the
same direction.
(e) Calculate the kinetic energy of trolley B and its suitcase after the collision. [E]
(f) What assumptions did you make in order to answer the above question? [M]
(g) This collision is described as inelastic. Explain clearly what happens to momentum
and kinetic energy in both elastic and inelastic collisions. [E]
QUESTION TWENTY TWO: RUA IN THE TROLLEY (NCEA 2008 Q2)
Rua then climbs onto a trolley and Tahi tows him with a rope, as shown in the diagram
below. Rua’s mass is 65 kg, the mass of the trolley is 11 kg. The tension force in the rope
attached to the trolley is 95 N, and the rope is at an angle of 45° to the ground. There is a 35
N friction force on the trolley.
(a)
Calculate the size of the trolley’s acceleration. [E]
(b)
The rope stretches 1.0 cm with the 95 N tension
force. Calculate the elastic potential energy stored
in the stretched rope. [E]
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QUESTION TWENTY THREE: MOTH IN THE WEB (NCEA 2011 Q3)
A spider spins a web in the garden and a moth gets caught in the web. The web stretches
downwards by 0.065 m when the moth of mass 0.003 kg is caught in it.
A graph for force against extension for the spider’s web is shown below.
Force (N)
Extension (m)
(a)
Explain why the formula W = Fd cannot be used to calculate the elastic potential
energy stored in the web when the moth gets caught in it.
Your explanation should include a statement of what should be used to calculate this
energy. [E]
(b)
Calculate the elastic potential energy stored in the web when the moth is caught in the
web. [M]
QUESTION TWENTY FOUR: THE POLE SWING
(NCEA 2008 Q2)
Rua goes across to the pole swing. The swing hangs on a
rope attached to a uniform beam, as shown in the diagram.
The beam is 3.0 m long and has a mass of 35 kg. The angle
between the steel wire and the beam is 37°. The tension
force in the steel wire is 1500 N.
(a) The force exerted on the beam by the steel wire
can be split into two components. Show that the
vertical component of the force exerted on the
beam by the steel wire is 900 N. [A]
(b) By calculating the torques on the beam about the
pivot, calculate the tension force in the rope. [M]
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Section 3 Momentum and Energy:
KNOW THE EQUATIONS (Energy, Momentum & Torque):
Symbol’s complete
name And SI unit
Situation where equation is most commonly
used (or notes about this equation).
Use your own paper
Ek  12 mv2
EK
1
m
v
Δ E p = mgΔ h
ΔEP
2
g
Δh
Ep  12 kx2
EP
3
k
x
W  Fd
W
4
F
d
P
W
t
P
t
ρ
p  mv
5
6
m
v
Δρ
Δ p = FΔ t
F
Δt
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7
QUESTION TWENTY FIVE: BALL DROP: (NCEA 2009, Q1 & Q2)
(a)
Jordan drops a ball onto the floor. The ball bounces up and down a few
times. Explain using energy considerations, why the height of bounce of
the ball, changes with time. [E]
(b)
Jordan then picks up the throws a basketball vertically upward. Describe
and explain what happens to the velocity and acceleration of the ball
while it is in the air. [E]
QUESTION TWENTY SIX: MOMENTUM (NCEA 2006 Q4)
Marama is driving her car home after her event, when she collides with a stationary van.
Assume there are no outside horizontal forces acting during the collision.
(a)
Name the physical quantity that is conserved in this collision. [A]
The mass of the car is 950 kg and the mass of the van 1700 kg.
The car is travelling at 8.0 m s–1 before the collision and 2.0 m s–1 immediately after the
collision, as shown in the diagram above.
(b)
Calculate the size and direction of the car’s momentum change. [E]
(c)
Calculate the speed of the van immediately after the collision. [M]
(d)
If the average force that the van exerts on the car is 3800 N, calculate how long the
collision lasts. [A]
(e)
Marama had a bag resting on the front seat. Use relevant physics concepts to explain
why the bag fell onto the floor during the collision. [E]
(f)
The front of modern cars is designed to crumple or gradually compress during a
collision. Use the idea of impulse to explain why this is an advantage for the people in
the car. [E]
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QUESTION TWENTY SEVEN: A COLLISION (NCEA 2005 Q2)
A car and its driver have a combined mass of 1200 kg. The car
collided with a stationary van of mass 1500 kg. The car and van
locked together after impact and from the marks on the road the
police were able to deduce that the wreckage moved at 4.0 m s –1
immediately after the collision.
(a)
Calculate the speed of the car just before it collided with the
van. [M]
(b)
(c)
State what physical quantity is conserved in the collision. [A]
State the condition necessary for the quantity you have named in (b) to be conserved.
[A]
(d)
The impact lasted for 0.50 seconds. Calculate the average force that the car exerted on
the van during the collision. [E]
(e)
Explain TWO features that a car has in order to reduce injury to the driver during a
collision. [E]
(f)
Use calculations to explain whether the collision was elastic or inelastic. [E]
QUESTION TWENTY EIGHT: THE HIGH JUMP (NCEA 2010 Q3):
Lucy is competing in a high jump event. She runs up to the bar, jumps over
it and lands on the mat.
(a)
Use physics principles to explain why it is better for Lucy to land on
the padded mat than it is to land on grass. [E]
QUESTION TWENTY NINE: JACQUIE & THE SOCCER BALL (NCEA 2011 Q2)
(a) While Jacquie is cycling at a speed of 16.8 m s–1, she collides with a soccer ball that is
rolling towards her at a speed of 8.0 m s–1. The soccer ball bounces off in the opposite
direction with a speed of 5.0 m s–1. Calculate Jacquie’s velocity (size and direction)
after the collision.
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You may ignore any effects of friction. Mass of Jacquie and her bike = 72.0 kg Mass
of soccer ball = 0.430 kg. [E]
(b) Explain what is meant by an elastic collision and an inelastic [E]
(c) Describe what you would need to do in order to determine whether this collision
between the bike and the soccer ball is elastic or inelastic. You are not required to
carry out any calculations. [E]
(d) Explain how the force exerted by the ball on Jacquie and her bike is dependent on the
duration of the time on impact, AND explain how the force exerted by the ball on
Jacquie and her bike is related to the force exerted by Jacquie and her bike on the ball.
[E]
QUESTION THIRTY: THE SHOT PUT (NCEA 2010 Q4)
Hamish is competing in the shot put. This involves throwing a 5.4
kg iron ball (the shot) as far as possible.
(a)
The shot starts from rest and accelerates for 0.25 s.
Calculate the average force that Hamish exerts on the shot
if it leaves his hand at 11 m s–1. [M]
When the shot lands, it rolls along the ground at 1.5 m s–1 and
collides head-on with a stationary shot which has a mass of 4.0
kg. The friction force is negligible during the collision.
After the collision, the 4.0 kg shot rolls forward at 2.4 m s–1 in the same direction that the
5.4 kg shot was initially rolling.
(b)
Without doing any calculations, what can you say about the total momentum
and the momentum of the 4.0 kg shot during the collision? Discuss your
answer. [E]
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(c)
Calculate the velocity (size and direction) of the 5.4 kg shot after the collision. [E]
QUESTION THIRTY ONE: HARRY IN THE CREASE (NCEA 2009, Q3)
In a game of cricket, the ball approaches the batsman with a speed of 21 m s –1.
The ball has a mass of 0.161 kg. The batsman hits the ball hard with an average
force of 2560 N, and the ball moves away in the opposite direction at 30.0 m s –1.
(a) Calculate the time the ball was in contact with the bat. [M]
(b) Express your answer to (b) to the correct number of significant figures.
State the reason for your choice of significant figures
for your final answer. [M]
(c) Harry is a fielder near the batsman. Explain, using
physics principles, why Harry usually pulls back his
hand while catching a ball. [E]
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QUESTION THIRTY TWO: THE SPECTATORS (NCEA 2010, Q5)
Aroha has a mass of 55 kg. She steps onto a bench to get a better view. The bench is 4.0 m
long. When she gets on to the centre of the bench, it bends downwards 3.00 mm.
(a)
(b)
Calculate the spring constant of the bench. Write your answer with the correct SI unit.
[M, A]
Calculate the elastic potential energy stored in the bench [A]
Aroha then walks towards one end so that she is 1.0 m away from support B.
(c)
The bench is in equilibrium. Explain what this means. [M]
(d)
Support B exerts a force of 420 N on the bench. Assuming the bench is uniform;
calculate the mass of the bench. [E]
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QUESTION THIRTY THREE: THE DUTY-FREE SHOP (NCEA 2007, Q4):
At a duty-free shop at the airport, a toy teddy bear is hanging at the end of a
spring. The spring is 51.0 cm long when hanging vertically. When the teddy bear
of mass 400 g is hung from the end of the spring, the length of spring becomes
72.0 cm.
(a)
Calculate the spring constant. Write a unit with your answer. [M,A]
(b)
Calculate the energy stored in the spring when a second toy of mass 300 g
is also hung along with the teddy bear on the spring. [M]
(c)
The 400 g teddy bear is now hung on a stiffer spring, which has double the
spring constant.
Discuss how this affects the extension and the elastic energy stored in the
spring. [E]
QUESTION THIRTY FOUR: THE HARD CHAIR (NCEA 2009,
Q3):
The springs (A) used in Harry’s car seats are different from the spring
(B) that Jill uses to hang a toy spider from the ceiling of her room. The
diagram shows two types of spring.
(a)
Compressing spring A by 0.20 m requires 150 J of work.
Stretching spring B by 0.30 m requires 210 J of work. By using appropriate working
and reasoning, show by calculation which spring is stiffer. [E]
24 | P a g e
Level 2 Physics Maniacal Mechanics Matching Madness
(plus common other things)
1. accelerate
11. couple
a) involved by reading a scale from an angle 2. acceleration
b)
due to gravity
c) stored in gravitational field when object is 4. average
d)
moved away relative to Earth
velocity
e) inwards acceleration as object moves in 6. centripetal force f)
circular path
g) the rate of change of dependent variable 8. components
h)
to independent variable in a graph
i) force needed to keep object moving in
10. continuous
j)
circular path
variable
k) the rate of change of velocity
12. deceleration
l)
13. displacement
m) length between two positions
3. accurate
5. centripetal
acceleration
7. collisions
9. conserved
15. elastic potential o) time taken for one revolution or event.
energy
17. frequency
q) makes the measurement consistently
larger (or smaller) than the true value
19. fulcrum
s) total displacement divided by total time
14. distance
16. force
18. friction
23. hertz
25. inelastic
y) measurement close to actual value
27. joules
aa) two equal and opposite forces that act 28. kinematic
at perpendicular distance apart to cause
equations of
rotation
motion
cc) negative acceleration
30. linear
29. kinetic energy
31. moment
33. net
35. parallax error
26. instantaneous
velocity
ee) two vectors at right angles which, when 32. momentum
added together, are equal to a single
vector
gg) number of revolutions or events in one 34. parallax
second
ii) used only when acceleration is not
36. period
changing
37. power
kk) object following parabolic path under
the force of gravity
38. precise
39. projectile
mm)
when measurements are closely
grouped together
40. proportional
25 | P a g e
quality that involves magnitude only
alternative name for standard form
quality used to describe how steep
a straight line is
alternative name for torque
quantity that requires a direction
n) alternative term for scientific
notation
p) rate at which objects change with
velocity when dropped on Earth
r) another term for resultant
20. fundamental
t)
units
u) makes the measurement equally likely to 22. gravitational
v)
be more or less than the true value
potential energy
w) turning or twisting effect about a pivot
24. impulse
x)
21. gradient
alternative name for pivot
rate of change of displacement
any type of graph that makes a
straight line with any gradient
rate of change of displacement at a
particular instant
z) apparent movement of two objects
due to the movement of the
observer
bb) rate of change of displacement of
one object in relation to another
dd) can take any value within a range
of values
ff) rate of change of distance
hh) change in momentum produced by
a force acting for a length of time
jj) rate of change of distance of
electromagnetic spectrum in
vacuum
ll) digits in a number or measurement
that are not being used as place
holders
nn) rate of doing work
41. random error
43.
45.
47.
49.
51.
42. relative velocity pp) distance traveled measured from
start position to finish
resultant
44. rounding error rr) seven units of the SI system from
which all others can be derived
scalar
ss) physical quantity of the mass multiplied 46. scientific
tt) equivalent single vector when two or
by the rate of change of displacement
notation
more vectors are acting on an
object
significant
uu) when the measuring scale does not
48. slope
vv) SI unit for the number of cycles
figures
give accurate value for nil measurements
per second
speed
ww) process of transforming energy form
50. speed of light xx) force in connected strings and
one form to another
ropes that tries to stretch them
spring constant yy) when two or more objects interact
52. standard form zz) SI unit of energy
53. systematic
error
55. torque
57. variables
59. velocity
61. work
oo) physical quantities that can have a
range of values
qq) when something stays constant
aaa)
produced when two surfaces come
in contact
ccc) when two qualities are related by a
constant ratio
eee)
property of object while in motion
54. tension
ggg)
where kinetic energy is not
conserved in collision
iii) push or pull in a particular direction
60. watt
26 | P a g e
56. uncertainty
58. vector
62. zero error
bbb)
force required to compress or
extend a spring one metre
ddd)
SI unit of rate of change of
work
fff) how a measurement could differ
from the true value
hhh)
stored in an extended or
compressed spring
jjj) introduced into calculations caused
by using partial previous answers