CAIE IGCSE Physics 1.5.1 Effects of Forces Topic Practice

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Covered syllabus points

1.5.1.1—Forces may produce changes in the size1.5.1.2—Load–extension graphs for an elastic1.5.1.3—Resultant of two or more forces acting1.5.1.4—An object either remains at rest or1.5.1.5—A resultant force may change the1.5.1.6—Solid friction as the force between1.5.1.7—Friction (drag) acts on an object1.5.1.8—Friction (drag) acts on an object1.5.1.9—Spring constant as force per unit1.5.1.10—Term ‘limit of proportionality’ for a1.5.1.11—Recall/use: F = ma1.5.1.12—Circular motion caused by a force

Question 1

[Maximum number: 7]

Question (a)

(a)

State two properties of an object that may be changed by the action of forces.
1.
2.

[ 2 ]

Question (b)

(b)

A chest expander is a piece of equipment used by athletes in a gym. Fig. 2.1 shows a chest expander that consists of five identical springs connected in parallel between two handles.

Fig. 2.1

Fig. 2.1

Each spring has an unstretched length of 0.63 m .
Two athletes are stretching the chest expander by pulling on the two handles in opposite directions.

[ 5 ]

Question (i)

(i)

The springs obey Hooke's law.

Explain what is meant by this statement.

[ 2 ]

Question (ii)

(ii)

Each athlete pulls the handle towards himself with a force of 1300 N .
1. State the tension in each spring.

tension =.........................................................

2. The chest expander stretches and each spring is now 0.94 m long.

Calculate the spring constant k of each spring.

k=
[ 3 ]

Question 2

[Maximum number: 6]

A force is a vector quantity.

Question (a)

(a)

A student suspends a spring from a clamp stand and measures the length l0l_{0} of the spring.

Fig. 2.1 shows the apparatus.

Fig. 2.1 (not to scale)

Fig. 2.1 (not to scale)

The student then suspends loads of different weights from the spring and measures the length of the spring for each load. He then plots a graph of the length of the spring against weight.

Fig. 2.2 is the graph that the student plots.

Fig. 2.2

Fig. 2.2

[ 6 ]

Question (i)

(i)

Using Fig. 2.2, determine the initial length l0l_{0} of the spring.

l0=l_{0}=
[ 1 ]

Question (ii)

(ii)

State what is meant by the limit of proportionality and, using Fig. 2.2, determine the weight of the load that causes this spring just to reach the limit of proportionality.
limit of proportionality
weight =

[ 2 ]

Question (iii)

(iii)

Using Fig. 2.2, determine the spring constant of this spring.
spring constant =

[ 3 ]

Question 3

[Maximum number: 3]

Question (a)

(a)

At night, the gas inside the balloon cools. The pressure of the air outside the balloon remains the same.

[ 3 ]

Question (i)

(i)

State whether the balloon rises, falls or remains stationary.

[ 1 ]

Question (ii)

(ii)

Explain your answer.

[ 2 ]

Question 4

[Maximum number: 2]

State two properties of an object that may be changed by the action of forces.
1.
2.

Question 5

[Maximum number: 1]

A force is a vector quantity.

A student suspends a spring from a clamp stand and measures the length l0l_{0} of the spring.

Fig. 2.1 shows the apparatus.

Fig. 2.1 (not to scale)

Fig. 2.1 (not to scale)

The student then suspends loads of different weights from the spring and measures the length of the spring for each load. He then plots a graph of the length of the spring against weight.

Fig. 2.2 is the graph that the student plots.

Fig. 2.2

Fig. 2.2

Using Fig. 2.2, determine the initial length l0l_{0} of the spring.

l0=l_{0}=

Question 6

[Maximum number: 2]

At night, the gas inside the balloon cools. The pressure of the air outside the balloon remains the same.

Explain your answer.

Question 7

[Maximum number: 2]

Fig. 1.1 shows a straight section of a river where the water is flowing from right to left at a speed of 0.54 m/s0.54 \mathrm{~m} / \mathrm{s}.

Fig. 1.1 (not to scale)

Fig. 1.1 (not to scale)

A swimmer starts at point P and swims at a constant speed of 0.72 m/s0.72 \mathrm{~m} / \mathrm{s} relative to the water and at right angles to the current.

When the swimmer is crossing the river, his actions produce a constant forward force on his body.

Explain why he moves at a constant speed.
[Total: 9]

Question 8

[Maximum number: 1]

A single force acts upon an object and the volume of the object does not change.
Which statement is correct?

A

The density of the object changes.

B

The velocity of the object changes.

C

The mass of the object changes.

D

The weight of the object changes.

Question 9

[Maximum number: 2]

A car accelerates uniformly in a straight line from rest at time t=0. At t=3.2 st=3.2 \mathrm{~s}, the speed of the car is 13.0 m/s13.0 \mathrm{~m} / \mathrm{s}.

On another day, the car in (c) travels a longer distance while it decelerates from 13.0 m/s13.0 \mathrm{~m} / \mathrm{s} to 0 m/s0 \mathrm{~m} / \mathrm{s}. The deceleration is constant.

Suggest and explain what causes the stopping distance to increase. suggestion
explanation

Question 10

[Maximum number: 1]

A ship sails in a straight line between two ports.
Fig. 1.1 shows the speed-time graph of the ship for the first 100 minutes of its journey between the two ports.

Fig. 1.1

Fig. 1.1

At a time not shown on the graph, the acceleration of the ship is 0.0087 m/s20.0087 \mathrm{~m} / \mathrm{s}^{2}. The total mass of the ship and its passengers is 2.3×107 kg2.3 \times 10^{7} \mathrm{~kg}.

Explain why the force on the ship due to the ship's engine is greater than the value you calculated in (c)(i).

Question 11

[Maximum number: 1]

A train has a total mass of 520000 kg . The train accelerates at 1.1 m/s21.1 \mathrm{~m} / \mathrm{s}^{2}.

The train uses electric motors.

Explain why the force on the train due to the motors is greater than the value calculated in (ii).

Question 12

[Maximum number: 3]

Fig. 2.1 is a graph that shows how the extension of a spring varies with the load suspended from it.

Fig. 2.1

Fig. 2.1

Determine the spring constant of this spring.
spring constant =

Question 13

[Maximum number: 1]

Fig. 2.1 is a graph that shows how the extension of a spring varies with the load suspended from it.

Fig. 2.1

Fig. 2.1

On Fig. 2.1, mark the limit of proportionality and label this point L .

Question 14

[Maximum number: 2]

A train has a total mass of 520000 kg . The train accelerates at 1.1 m/s21.1 \mathrm{~m} / \mathrm{s}^{2}.

Calculate the force required to produce an acceleration of 1.1 m/s21.1 \mathrm{~m} / \mathrm{s}^{2} for this train.

force =

Question 15

[Maximum number: 3]

Question (a)

(a)

Fig. 2.2 shows a car travelling at constant speed around corner A on a road.

Fig. 2.2

Fig. 2.2

[ 3 ]

Question (i)

(i)

On Fig. 2.2, mark with an arrow the direction of the resultant force acting on the car as it travels around corner A.

[ 2 ]

Question (ii)

(ii)

Corner B has a smaller radius than corner A . The car travels at the same speed around corner B as around corner A.

State how the resultant force changes due to the car travelling around a corner of smaller radius.

[ 1 ]
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