CAMBRIDGE IGCSE™ COMBINED AND CO-ORDINATED SCIENCES: PHYSICS WORKSHEET P2.
2C
Name Date
P2.2C: Work and power
1 When an object is lifted vertically, it gains gravitational potential energy. As
the object gains gravitational potential energy, work is done on the object.
Use these statements, and the equations for both gravitational potential energy
and work done, to show that work and energy are equivalent.
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2 a Write the equation for work done, W, in terms of force, F, and distance
moved in the direction of the force, d.
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b A force of 150 N pulls a box through a distance of 5 m as shown in Figure
2.1.
Figure 2.1
Calculate the work done on the box. Include the unit with your answer.
work done = ____________
c The box is pulled again, this time with a force that is twice as large. The time
taken for the box to travel 5 m decreases by half. Compare this with the first
time the box was pulled.
Underline the correct option to complete each of these sentences:
i The work done on the box stays the same / doubles / increases by
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© Cambridge University Press & Assessment 2023
CAMBRIDGE IGCSE™ COMBINED AND CO-ORDINATED SCIENCES: PHYSICS WORKSHEET P2.2C
four times.
ii The power used to pull the box stays the same / doubles / increases
by four times.
3 a A learner stands on the floor. The weight of the learner on the floor is
650 N.
Explain why this force does no work on the floor.
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b Another learner carries a heavy book across a horizontal floor. The
height of the book above the floor does not change.
Explain whether the learner does any work on the book.
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c Another learner has to raise a heavy box through a vertical height of 0.5
m.
The learner can either lift the box vertically or push the box up a ramp.
State one advantage and one disadvantage of pushing the box up the
ramp compared with lifting.
Advantage: ____________________________________________________________________
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Disadvantage: _________________________________________________________________
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4 A company sells electric motors. The price of a motor depends on its power.
a Explain what is meant by power.
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b One of the motors is tested by lifting a load vertically.
The motor can increase the gravitational potential energy of a load by
20 000 J in 10 s.
i Calculate the power developed by this motor. Show your working and
include the unit with your answer.
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© Cambridge University Press & Assessment 2023
CAMBRIDGE IGCSE™ COMBINED AND CO-ORDINATED SCIENCES: PHYSICS WORKSHEET P2.2C
power developed = ____________
ii Another motor has half the power of the first motor. State the time
taken for the motor with half the power to lift the same load through
the same distance.
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