Edexcel IGCSE Physics C Work and Power Questions

Practise using work, energy and power equations in mechanical contexts, with unit conversions, graph evidence and store changes.

Exam points

calculate work done from force and distance, including circular paths or ramp distances
apply GPE and KE equations to find transferred, lost or stored energy in moving objects
calculate power from energy and time, then judge graph conclusions about mass and power

Covered syllabus points

4.11 Work done equation 4.12 Work and energy transfer 4.13 Gravitational potential energy 4.14 Kinetic energy equation 4.15 Energy conservation links 4.16 Power 4.17 Power equation

[Maximum number: 12]

A student uses this apparatus to investigate the force needed to pull a block along a ramp.

Figure for Question 1 — Edexcel IGCSE Physics

(a)

State the formula linking work done, force and distance moved in the direction of the force.

[ 1 ]

(b)

The student pulls the block 0.89 m along the ramp with a force of 26 N . Show that the work done on the block by the 26 N force is about 23 J .

[ 2 ]

(c)

The block has a mass of 1.3 kg and moves vertically upwards 0.11 m.

Calculate the increase in the gravitational potential energy (GPE) store of the block between the bottom and the top of the ramp.

increase in GPE = ............ J

[ 3 ]

(d)

Explain why the work done to move the block along the ramp is greater than the increase in the GPE store of the block.

[ 2 ]

(e)

The student suggests it is better to use a less steep ramp to raise the block through the same vertical height.

Discuss an advantage and a disadvantage of using a less steep ramp.

[ 4 ]

[Maximum number: 4]

The photograph shows a toy car. When the toy car is pulled backwards, energy is stored in the elastic store as the rubber band is twisted.

Figure for Question 2 — Edexcel IGCSE Physics

When the car is released, some of the energy from the elastic store is transferred to the kinetic store of the car.

The remaining energy is transferred into the thermal store of the surroundings.

(a)

The car is pulled backwards again.

When released, 45 J of energy transfers into the car's kinetic store.
The car travels a distance of 7.5 m during this energy transfer.

[ 4 ]

(i)

State the useful work done on the car.

work done = ............ J

[ 1 ]

(ii)

Calculate the mean accelerating force acting on the car.

accelerating force = ............ N

[ 3 ]

[Maximum number: 2]

A student uses this apparatus to investigate how the efficiency of an electric motor varies with its input voltage.

Figure for Question 3 — Edexcel IGCSE Physics

This is the student's method.
- connect the electric motor to a d.c. power supply and a joulemeter
- attach a 1.0 kg mass to the electric motor using a length of string
- set the voltage of the power supply to 10 V and switch on the power supply
- switch off the power supply when the mass has been lifted through a distance of 50 cm
- record the input energy to the motor from the joulemeter
- calculate the energy transferred to the gravitational store of the mass
- calculate the efficiency of the motor

The student repeats this process, setting the power supply to a different voltage each time.

Show that the gravitational store of the 1.0 kg mass increases by 5.0 J when it is lifted through a distance of 50 cm .

[Maximum number: 1]

The photograph shows a toy car. When the toy car is pulled backwards, energy is stored in the elastic store as the rubber band is twisted.

Figure for Question 4 — Edexcel IGCSE Physics

When the car is released, some of the energy from the elastic store is transferred to the kinetic store of the car.

The remaining energy is transferred into the thermal store of the surroundings.

The car is pulled backwards again.

When released, 45 J of energy transfers into the car's kinetic store.
The car travels a distance of 7.5 m during this energy transfer.

State the useful work done on the car.

work done = ............ J

[Maximum number: 3]

A student uses a computer simulation to investigate the motion of particles in a gas.
He records the pressure of the gas and the mean speed of the particles in the gas at different temperatures.

The graphs show his results.

Graph 1

Graph 2

The student then calculates the kinetic energy of a single gas particle at each temperature.

The mass of a single gas particle is $5.3 \times 10^{-26} \mathrm{~kg}$ .

Calculate the average kinetic energy of a gas particle when the temperature of the gas is $100^{\circ} \mathrm{C}$ .

Marking points:
- recall of kinetic energy formula
- substitution
- evaluation

Example:
$\mathrm{KE}=\frac12\times\text{mass}\times\text{speed}^{2}$ $\mathrm{KE}=0.5\times5.3\times10^{-26}\times520^{2}$ $\mathrm{KE}=7.2\times10^{-21}\ \mathrm{J}$

Accept:
- ECF from part (i)
- $7.16\times10^{-21}$ to $7.31\times10^{-21}\ \mathrm{J}$

Marking guidance:
- power-of-ten error scores -1

[Maximum number: 2]

A student uses this apparatus to investigate the force needed to pull a block along a ramp.

Figure for Question 6 — Edexcel IGCSE Physics

Explain why the work done to move the block along the ramp is greater than the increase in the GPE store of the block.

[Maximum number: 1]

Kori Nuclear Power Plant in South Korea is one of the world's largest nuclear fission power stations.

Figure for Question 7 — Edexcel IGCSE Physics

Kori has a maximum power output of $7.49 \times 10^{9} \mathrm{~W}$ .

State what is meant by the term power.

[Maximum number: 3]

Energy is transferred from the Sun to the Earth.

Solar panels use energy from the Sun to heat water.

Figure for Question 8 — Edexcel IGCSE Physics

The total area of the solar panels is $15 \mathrm{~m}^{2}$ .

Each $1.0 \mathrm{~m}^{2}$ of the solar panels receives 1000 J of energy per second from the Sun. Show that the total energy transferred to the solar panels in 2 hours is about 100 MJ .

All question bank results loaded

Covered syllabus points

Question 1

Question (a)

Question (b)

Question (c)

Question (d)

Question (e)

Question 2

Question (a)

Question (i)

Question (ii)

Question 3

Question 4

Question 5

Question 6

Question 7

Question 8