Edexcel IGCSE Physics (c) Work & power Question Bank
Practise using work, energy and power equations in mechanical contexts, with unit conversions, graph evidence and store changes.
- Syllabus
- First assessment 2019
- Course
- Physics 4PH1
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
(c) Work and power question 1
A student uses this apparatus to investigate the force needed to pull a block along a ramp.
Question (a)
(a)
State the formula linking work done, force and distance moved in the direction of the force.
[ 1 ]
Question (b)
(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 ]
Question (c)
(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 ]
Question (d)
(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 ]
Question (e)
(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 ]
(c) Work and power question 2
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.
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.
Question (a)
(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 ]
Question (i)
(i)
State the useful work done on the car.
work done = ............ J
[ 1 ]
Question (ii)
(ii)
Calculate the mean accelerating force acting on the car.
accelerating force = ............ N
[ 3 ]
(c) Work and power question 3
A student uses this apparatus to investigate how the efficiency of an electric motor varies with its input voltage.
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 .
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