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WAEC Physics 2021 Paper

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Question : 36

Total: 50

A force of 10 N, acting continuously, increases the kinetic energy of an object from 20.J to 60 J. Find the distance moved by the object.

200m
40m
4m
400m

Solution:

Concept:

The work-energy theorem states that the work done by a force equals the change in kinetic energy.

Explanation:

Work done,

W = F \times s

, where

F = 10\ \mathrm{N}

and

s

is the distance.

Change in kinetic energy,

\Delta K = 60\ \mathrm{J} - 20\ \mathrm{J} = 40\ \mathrm{J}

.

According to the work-energy theorem:

F \times s = \Delta K

10 \times s = 40

s = \frac{40}{10} = 4\ \mathrm{m}

Answer:

C.

4\ \mathrm{m}

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