Download UNIT 2 - Harrison High School

PHYSICS 122Y - FINAL EXAM REVIEW
(Use separate paper to define terms and answer questions.)
You will be assigned portions of these questions each day for homework. Each day you will be
given a bonus assignment in which you may use your homework to complete. The points from the
bonus assignment will be added to the categories in the gradebook.
UNIT 1a: Science Habits of Mind
Define these terms:
variable
accuracy
direct relationship
control
precision
inverse relationship
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You decide to measure the effect of steroids on the growth rate of rats. What would be a good control
group? rats without the steroids
 Marlon hypothesizes that by decreasing the number of donuts he ate would decrease his weight. What is
his independent variable? Number of donuts
 Mrs. Smith proposed that by increasing the catnip in Kitten’s dinner, it would increase her cat’s activity.
What is the dependent variable? The activity level of the cats
 Which type of graph shows changes or trends over time? Line graph
 Explain the difference between accuracy and precision using the dartboard example. When playing
darts, accuracy would be hitting the bullseye; precision would be having all of your darts with within the
same general area or having all of your darts hit in the same area
 When would you use a bar graph? Bar graphs are used to show amounts, such as the number of students
taking biology, physics or chemistry per period
UNIT 1b
KINEMATICS (Linear Motion)
Define these terms:
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instantaneous speed
acceleration
displacement
average speed
distance
If an object falls in a vacuum, describe its velocity and acceleration. Its velocity will increase but its
acceleration (the rate at which speed changes) will stay the same
Describe the speed of an object thrown straight up. As the object goes higher and higher, its velocity
will decrease to zero, then it will fall back down and as it falls its speed will increase until it hits the
ground. On Earth, the speed up and down will change by a factor of 10 m/s per second.
In the question above, does the speed of the object ever reach 0? Does the acceleration ever reach 0?
The speed will reach zero at the top (apex) of the object’s path. The acceleration will only be zero
when the object has hit the ground and no longer moving.
A car goes from 15 m/s to 30 m/s in 2 seconds. What is the car’s acceleration? 30-15 / 2 = 7.5 m/s2
What is the meaning of the slope in a distance vs. time graph? In a velocity vs. time graph? The
slope on a distance-time graph is a measure of the objects speed. For a velocity-time graph the slope
represents the acceleration of the object.
UNIT 2
NEWTON’S LAWS
Define these terms:
law of inertia
Coefficient of friction
friction
static friction
terminal velocity
kinetic friction
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If a car goes around a curve and starts to hydroplane, what direction will the car travel in? In the
direction that is was going when it started to hydroplane, the direction won’t change.
If a 40 N force and a 60 N force act on an object in opposite directions, what is the net force? 60-40
= 20 N
If a 30 N force and a 20 N force act on an object in the same direction, what is the net force? 30 + 20
= 50 N
A man weighs 95 N. What is his mass? 95/10 = 9.5 kg
If the mass of a cart doubles but the force stays the same, what happens to its acceleration? The
acceleration reduces by half
Forces always occur in __________________________. pairs
A bat hits a baseball (action force). What is the reaction force? The baseball hitting the bat
A 150 N object hangs from a container supported by 2 ropes. What is the tension force on each
rope? 150/2 = 75 N
A bug hits a moving cyclist. Compare the forces exerted on each and the acceleration of each. The
force of impact for the bug is the same as the force of impact for the cyclist. However, because the
cyclist has more mass, the same force has less effect on its acceleration. Yet the bug, with such a
small mass will experience greater acceleration.
A push of 50 N on a 20 kg object experiences 10 N of friction. At what rate will the object
accelerate? 50-10 / 20 = 2 m/s2
For a ball to keep rolling across a floor, must there be a horizontal force acting on it if friction is
present? Explain. Friction opposes motion and will cause an object to slow down. Therefore, if the
object is to keep moving at the same speed, there must be a force (equal to that of the friction force)
to keep the object moving.
You push a 5 kg crate across the floor at constant speed. If the coefficient of friction between the
crate and the floor is 0.5, what is the force of friction? Normal force = 5 (10) = 50 N; F = 0.5(50) =
25 N
A ball is hit off a tee. If the ball goes from rest to 80 m/s in 1.5 seconds and the ball has a mass of
0.5 kg, what was the force of impact? Ft = mv; F = mv/t = (0.5)(80-0) / 1.5 = 26.7 N
How do the coefficients of static and kinetic friction compare to each other? Static friction is larger
than kinetic; it’s harder to get something that’s stationary moving than it is to keep something
moving that’s already in motion.
Which is always greater, static or kinetic friction, and why? Static friction is larger than kinetic; it’s
harder to get something that’s stationary moving than it is to keep something moving that’s already
in motion.
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UNIT 3
Centripetal, Gravitational, Rotational Forces, Parabolic Motion
Define these terms:
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torque
vertical motion
centripetal force
magnitude
centrifugal force
horizontal motion
When using a wrench to loosen a nut, the force exerted on it must be ___perpendicular__
to the lever arm. (Hint: direction)
Where is the linear speed greatest on a merry-go-round: the outside or inside horse? Outside horse
Where is the rotational speed the greatest on a merry-go-round: outside or inside horse? Same
When trying to balance a meterstick (50 cm is the middle) and a 25 N weight is placed at the 30 cm
mark, where should a 35 N weight be placed to balance it? (25 ∙ 20) = (35 ∙ X) X= 14.3 cm from
fulcrum or 64.3 cm mark on meterstick
What is the resultant of two vectors, 5 m east and 4 m east? 5 + 4 = 9 m east
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How do the horizontal and vertical velocities of a projectile compare? They act independently of
each other; one has no impact on the other
If a boat travels 20 km/h East while the water moves 6 km/h South, what would be the resultant
speed of the boat? 202 + 62 = 400 + 36 = √436 = 20.88 km/h
Describe the sign rules (+ or -) for velocity and for the acceleration due to gravity for vertical
motion. + = up , - = down
UNIT 4
MOMENTUM AND IMPULSE
Define these terms:
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momentum
Impulse
Increase the time of impact = ___decrease__________ force of impact.
What is the formula and unit for momentum? p = m∙v ; unit = kg ∙ m/s
What is the momentum of an object that has a mass of 40 kg and a velocity of 10 m/s? 40 ∙ 10 =
400 kg ∙ m/s
A 10,000 kg truck traveling 20 m/s hits a wall and comes to a stop in 0.5 seconds. What is the force
of impact? (F ∙ 0.5) = (10,000 ∙ 20)
(F ∙ 0.5) = 200,000
F = 400,000 N
A 10 kg fish moving 3 m/s sneaks up on and eats a 2 kg fish that was floating in the same spot.
After the big fish has dinner, how fast is he going after the two fish become one? (10 ∙ 3) + (2 ∙ 0) =
(10+2)(v)
30 = (12)(v)
v = 2.5
What’s the difference between elastic and inelastic collisions? Elastic = no heat or deformation;
objects do not stick together
Inelastic = heat and deformation occurs; objects stick together
UNIT 5
WORK, ENERGY, POWER
Define these terms:
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power
Watt
Energy
kinetic energy
potential energy
convection
conduction
Joule
work
radiation
An object has 3000 J of potential energy. How much kinetic energy does it have right before
impact? 3000 J – all the potential energy is converted to kinetic
A 100 N rock is moved 15 m in 2 seconds. How much power was exerted? (100)(15)/2 =
750 watts (J/s, Nm/s)
Wasted energy is released as _____heat________.
A lever is used to move a 100 N object 2 m. The user had to push on the lever with 50 N.
How far did she have to push the lever down? (100)(2) = (50)(d) d= 4 m
How much work is done when 75 N of books are lifted 3 m? (75)(3) = 225 Nm or J
600 N Nate climbs 5 m in 10 seconds. How much power does he have? (600)(5)/10 = 300
watts (Nm/s or J/s)
Sally and Melissa try to move their freezer. They both push on it for 5 minutes. It does not
budge. How much work did the girls do? None – nothing moved
A 30 N book sits on the railing of a deck, which is 5 m off the ground. How much potential
energy does the book have? (30)(5) = 150 J or Nm
A 90 kg runner runs 10 m/s. How much kinetic energy does he have? (1/2)(90)(102) = 4500
J or Nm
A 15kg rock is about to fall off a 60 meter cliff. How much kinetic energy does it have right
before impact? (15)(10)(60) = 9000 J or Nm (PE = KE)
What direction does thermal energy flow? Hot to cold
What does temperature measure? Average kinetic energy of the atoms or molecules
What is heat? Movement of thermal energy from high to low
An ice cube sits on a table. How is energy transferred? (conduction, convection, radiation)
UNIT 6
WAVES AND SOUND
Define these terms:
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beats
refraction
constructive interference
transverse wave
wavelength
diffraction
destructive interference
compressional wave
reflection
frequency
amplitude
What is the beat frequency when a tuning fork with a frequency of 268 Hz and one of 272 Hz are
sounded together? 4 Hz
Sound travels best in _______________________, followed by _____________________ and worst
in _____________________. (Hint: states of matter) solids, liquids, gases
A wave has frequency of 0.1 Hz and a wavelength of 10 m. What is the wave’s speed? (0.1)(10) =
1 m/s
A particular sound has a 3.5 m wavelength and is traveling 340 m/s. What is its frequency?
350/3.5 = 100 Hz
The speed of a wave depends on ______________. wavelength times frequency OR type of medium
The frequency of a wave depends on ______________. wavelength
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When a wave passes from one medium into another, the ___________ and __________ change.
Speed and wavelength
The bending of wave when it passes from one medium to another and the speed changes is called
___________. refraction
The spreading of a wave around an obstacle or through an opening is called _______________.
diffraction
The bouncing of a wave off a barrier is called _________________. reflection
All waves carry ________________. energy
Describe the difference between a longitudinal (compressional) and a transverse wave in the manner
in which they carry energy vs. the direction that the matter moves. Longitudinal waves are created
when particles vibrate in the same direction in which the energy moves (both the particle and energy
move in the same direction); transverse waves have particles that vibrate in a direction that is
perpendicular to the direction the energy moves
Give an example of a transverse, mechanical wave. Water waves, also possibly some earthquake
waves
Give an example of a transverse, non-mechanical wave. Anything electromagnetic (light, radio, xrays, etc)
Give an example of a compressional wave. sound
Compressional waves require a _________ to propagate (move). Medium (matter)
UNIT 7 - ELECTRICITY
Define these terms:
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current
direct current
series circuit
potential difference
alternating current
parallel circuit
resistance
Calculate the current flowing through a 15 Ω electric blanket connected to a 120 V outlet. 120/15 = 8A
Calculate the current that flows through a coffee pot with 15 Ohms of resistance connected to a 120 V
outlet. 120/15 = 8A
How much resistance do your toes have if 0.01 A of current run through them when they tough a 9 V
battery? 9 / 0.01 = 900 Ω
Describe the placement of an ammeter and a voltmeter in a circuit. Ammeters are placed within the path
or circuit whereas voltmeters are place outside the circuit on both sides of the object whose voltage drop
is to be measured
What is the difference between AC and DC current? AC means the current moves back and forth (cycles)
as it moves through the circuit (like the current in your home); DC means the energy flows in one
direction (usually from one end of a battery to the other end)
What is the equivalent resistance of 2 Ω, 6 Ω, and 10 Ω resistors in a series circuit? 2 + 6 + 10 = 18 Ω
What is the equivalent resistance of 4 Ω, 6 Ω, and 12 Ω resistors in a parallel circuit? ¼ + 1/6 + 1/12 =
3/12 + 2/12 + 1/12 = 6/12; 12/6 = 2 Ω
What (V, I, or R) remains the same for a series combination of resistors? I- current
What (V, I, or R) remains the same for a parallel combination of resistors? V- voltage
UNIT 8: NUCLEAR PHYSICS
Define these terms: atomic mass
fusion
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isotope
radioactivity
Draw the decay reaction for the beta decay of phosphorus-32. 1532P >
Draw the alpha decay of Am-240. 95240Am > 24He + 93236Np
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fission
0
e + 16 32S
 Which 2 subatomic particles are found in the nucleus of an atom and which one of these holds the
nucleus together? Protons and neutrons are in the nucleus; it’s the neutrons that act as the glue holding the
nucleus together
 What type of nuclear reaction occurs in the Sun and stars? fusion
 Determine the number of protons, neutrons and electrons in 212 Po. p = 84, n = 128, e = 84
 If isotope X had a half life of 15.0 years, how much of isotope X would be left after 105 years had past
if you started with 200 g? 105 / 15 = 7 half lives; 200 divided in half seven times = 1.5625 ( 200 > 100 >
50 > 25 > 12.5 > 6.25 > 3.125 > 1.5625)
 You have 400 g of isotope Y, and after 30 years you only have 50 g left. What is the half-life of isotope
Y? 400 > 200 > 100 > 50; therefore 3 half lives; if all three half lives are 30 years, then each half life is 10
years