Download National 4 Physics Homework 1 Average and Instantaneous Speed

National 4 Physics
Homework 1
1.
Average and Instantaneous Speed
Two pupils wish to measure the average speeds of cars as they
travel along Law Road.
State what equipment they would use and how they would carry
out the experiment.
Also state how they would calculate the average speed from their
measurements?
2.
Show, using labelled diagram, how you would measure the
instantaneous speed of a trolley at the point shown on the diagram
State what equipment they would use and how they would carry
out the experiment.
Also state how they would calculate the instantaneous speed from
their measurements?
[Turn over
3.
State whether the following are average speeds or instantaneous
speeds.
a. The speed of train travelling between Edinburgh and North
Berwick.
b. The speed of a car on a speedometer.
c. The speed of a roller coaster at bottom of a loop.
d. The speed of a car between two lamp-posts.
e. The speed of a golf ball as it leaves the club.
4.
A top class sprinter covers the 100m in a time of 10 seconds.
Calculate the sprinter's average speed.
5.
How long will it take a Formula 1 car to travel one lap around a 5 km
long circuit if it is travelling at an average speed of 180 km/h?
End of Homework
Homework 2
Acceleration
1.
Write a sentence explaining the word “acceleration”
2.
Calculate a car’s acceleration if its speed increases by 12 m/s in a
time of 3 s.
3.
A car starts from rest and reaches a speed of 40 m/s in a time of 8
seconds. Calculate its average acceleration.
4.
A sprinter is found to take 3.0 seconds to reach his top sprinting
speed of 10.5 m/s in a straight line. Calculate his average
acceleration.
5.
What is the acceleration of a lorry which increases its speed from 5 m/s
to 15 m/s in 40 seconds?
End of Homework
Homework 3
1.
Speed-time graphs
Look at the graph. This shows the speed of a car over a short
journey. Use the graph to answer these questions.
Speed/m/s
B
40
C
30
20
10
D
A
10
20
30
40
50
Time/s
a. Describe the car’s motion between:
A and B;
B and C;
C and D.
b. Estimate the car’s speed after 10 seconds.
2.
A car's speed is recorded over a period and the results are show in
the table below:
TIME (s)
0
2
4
6
8
10
SPEED (m/s)
0
6
12
18
24
30
a. Plot a graph of the car's motion over this 10-second period.
b. From the graph, find the car's speed 5 seconds into its journey.
c. Describe the car’s motion over the 10 seconds.
[Turn over
3. A small aeroplane lands on a runway and brakes. The speed time graph
below represents the speed of the aeroplane from the instant the pilot
touches down on the runway until it stops.
a.
When did the pilot brake?
b.
Calculate how far the aeroplane travelled before braking.
c.
Calculate how far the aeroplane travelled after the pilot braked.
End of Homework
Homework 4
1.
Weight, mass and gravitational field strength
a. A force is defined by the three main effects it may have on an object.
Name any two of these.
b. A tennis player applies a force on the ball with
his racquet. Give one effect on the ball that
proves a force has been applied.
2.
Describe how a Newton Balance can be used to measure the size of
a force.
3.
The value of gravitational field strength is given in the table below
for some objects in our Solar System.
a. What value of gravitational field strength is used to calculate weight
on Earth? (Remember the unit!)
b. If a pupil had a mass of 60 kg, what
would their weight be on:
i. Earth
ii. Mars
iii. Pluto
Earth
Jupiter
Mars
Mercury
Moon
Neptune
Saturn
Sun
Venus
Uranus
Pluto
End of Homework
g (N/kg)
10
26
4
4
16
12
11
270
9
11 7
42
Homework 5
1.
Friction
Look at the cyclists in the picture below.
a. Identify two ways in which friction acting against the bicycles or
cyclists has been reduced.
b. On other occasions, it is useful to increase the amount of friction
acting.
i.
Identify one place on a bicycle where friction is increased.
ii.
Explain why friction should be increased.
c. What type of energy is produced whenever a moving object
meets friction?
End of Homework
Homework 6
1.
Newton’s First Law
Copy and complete the following:
An object will remain at _ _ _ _ or continue to travel at a _ _ _ _ _ _ _ _
speed in a straight line, unless an _ _ _ _ _ _ _ _ _ _ force acts.
Therefore if the forces acting on the object are _ _ _ _ _ _ _ _ then the
object will either be _ _ _ _ _ _ _ _ _ _ or will be moving at a
_ _ _ _ _ _ _ _ speed.
2.
Explain how a seat belt can prevent injury in a car crash.
3.
When a sky diver jumps out a plane, they start to accelerate towards the
ground. After a short while, they reach a terminal velocity.
a.
b.
4.
State the meaning of terminal velocity.
Why does the sky diver reach a terminal velocity?
A spacecraft is travelling through outer space. Its engine is switched off.
a.
Describe and explain the motion of the spacecraft:
b.
The spacecraft's engine is now switched on.
End of Homework
Homework 8
1.
Force and Newton’s 2nd Law
Look at the pairs of forces acting on the objects below. In each case,
state the resultant force and the direction in which it is acting.
a.
b.
5N
10 N
12 N
20 N
2.
What will happen to an object if the forces acting on it are unbalanced?
3.
Calculate the force required to accelerate a car of mass 1 000 kg
at 5 m/s2.
4.
A man pushes a wheelbarrow of mass 25 kg with a force of 25 N.
Calculate the acceleration of the wheelbarrow.
5.
The diagram below illustrates the forces acting on a motorbike. The
combined mass of the bike and rider is 125 kg.
200 N
700 N
a. What is the size of the resultant force acting on the bike?
b. Calculate the acceleration of the bike.
End of Homework
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