CAIE IGCSE Physics 1.7.1 Energy Questions

Covered syllabus points

1.7.1.1—Energy may be stored as kinetic 1.7.1.2—Energy is transferred between stores 1.7.1.3—Principle of the conservation of 1.7.1.4—Kinetic energy: Ek = 1/2 mv^2 1.7.1.5—Recall/use: for the change in 1.7.1.6—Principle of the conservation of

[Maximum number: 1]

Fig. 2.1 shows solar-powered traffic warning lights.

Fig. 2.1

The energy from the solar cell is stored in a battery.

Name the energy store in the battery.

[Maximum number: 3]

A student drops a heavy ball from a vertical height of 1.8 m above the ground. The ball then falls to the ground. It does not bounce after hitting the ground.

Describe the transfers of energy of the ball between stores from when the ball begins to fall to when it reaches the ground.

[Maximum number: 4]

A girl holds a rubber ball out of a window of a tall building. The mass of the ball is 0.20 kg . The ball is at rest 10 m above a concrete path.

(a)

Calculate the gravitational potential energy of the ball relative to the concrete path.

gravitational potential energy =

[ 2 ]

20 J
$\left(\Delta . E_{\mathrm{p}}=\right) m g(\Delta) h$ OR $0.2(0) \times 9.8 \times 10$

(b)

The girl releases the ball and it falls towards the path. The ball strikes the path and bounces vertically upwards.

Fig. 1.1 shows the ball falling towards the path.

Fig. 1.1

The speed of the ball immediately before it strikes the path is $14 \mathrm{~m} / \mathrm{s}$ .
The speed of the ball immediately after it strikes the path is $12 \mathrm{~m} / \mathrm{s}$ .

[ 2 ]

(i)

Calculate the kinetic energy of the ball immediately after it strikes the concrete path.

kinetic energy =

[ 2 ]

14 J
$\left(E_{\mathrm{k}}=\right) \frac{1}{2} m v^{2} \mathbf{O R} \frac{1}{2} \times 0.2(0) \times 12^{2}$

[Maximum number: 2]

A girl holds a rubber ball out of a window of a tall building. The mass of the ball is 0.20 kg . The ball is at rest 10 m above a concrete path.

The girl releases the ball and it falls towards the path. The ball strikes the path and bounces vertically upwards.

Fig. 1.1 shows the ball falling towards the path.

Fig. 1.1

The speed of the ball immediately before it strikes the path is $14 \mathrm{~m} / \mathrm{s}$ .
The speed of the ball immediately after it strikes the path is $12 \mathrm{~m} / \mathrm{s}$ .

Calculate the kinetic energy of the ball immediately after it strikes the concrete path.

kinetic energy =

14 J
$\left(E_{\mathrm{k}}=\right) \frac{1}{2} m v^{2} \mathbf{O R} \frac{1}{2} \times 0.2(0) \times 12^{2}$

[Maximum number: 3]

Fig. 2.1 shows two identical trolleys, P and Q, held at rest on a frictionless horizontal surface. A load is fixed to trolley P .

Fig. 2.1

There is a compressed spring between trolley P and trolley Q .
The trolleys are released. As the spring expands, it pushes the trolleys apart.
Trolley Q moves to the right at a constant speed of $0.36 \mathrm{~m} / \mathrm{s}$ .
The mass of each trolley is 1.2 kg . The mass of the load on trolley P is 1.5 kg .
The spring has negligible mass.

Calculate:

the kinetic energy of trolley Q when it moves at $0.36 \mathrm{~m} / \mathrm{s}$ .
kinetic energy of Q =

0.078J
(k.e. = ) $\frac{1}{2} m v^{2}$ OR (k.e. = ) $\frac{1}{2} \times 1.2 \times 0.36^{2}$
(k.e. = ) $\frac{1}{2} \times 1.2 \times 0.36^{2}$

[Maximum number: 3]

A ball of mass 130 g is launched from the ground at an initial velocity of $14 \mathrm{~m} / \mathrm{s}$ vertically upwards. It decelerates until it is at rest momentarily at a height h above the ground.

Calculate h. Ignore the effect of air resistance.

10 m
(initial) $E_{\mathrm{k}}$ of ball =( maximum $) E_{\mathrm{p}}$ gained $\mathbf{OR} \frac{1}{2} m v^{2}=m g h$ $(h=) E_{\mathrm{p}} / m g \mathbf{OR}(h=) \frac{1}{2} V^{2} / g \mathbf{OR}(h=) 12.74 /(0.13 \times 9.8)(=10 \mathrm{~m}) \mathbf{OR}(h=)\left(\frac{1}{2} \times 196\right) / 9.8$

[Maximum number: 1]

A box is initially at rest at the top of a rough slope.
The box slides down the slope.
The weight of the box is 20 N .
The slope is 4.0 m long and 2.0 m high.

Figure for Question 7 — CAIE IGCSE Physics

The box does 10 J of work against friction as it slides down the slope.
What is the speed of the box as it reaches the bottom of the slope?

$5.4 \mathrm{~m} / \mathrm{s}$

$6.3 \mathrm{~m} / \mathrm{s}$

$7.1 \mathrm{~m} / \mathrm{s}$

$9.5 \mathrm{~m} / \mathrm{s}$

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CAIE IGCSE Physics 1.7.1 Energy Topic Practice

Covered syllabus points

Question 1

Question 2

Question 3

Question (a)

Question (b)

Question (i)

Question 4

Question 5

Question 6

Question 7