# Learn It: Sample Questions Using the Work Equation

##### Question 1

Calculate the work done when a force of 10 newtons acts through a distance of 50 metres in the direction of the force.

Worked solution:

W = Fs
= 10 × 50
= 500 J                 Ans.  500 J

##### Question 2

A girl pulls a sledge a distance of 100 metres. If the force exerted by the girl is 80 newtons in the direction in which the sledge is moving, calculate the work done.

Worked solution:

W = Fs
= 80 × 100
= 8000 J
= 8 kJ                   Ans.  8 kJ

##### Question 3

A car of mass 900 kg accelerates at 3 ms-2 from rest. How much work is done after it has travelled 100 metres?

Worked solution:

There are two steps involved in solving this problem:

Step 1 :  Calculate the force required to cause the acceleration.

Recall: Force = mass × acceleration

F = ma
F = 900 × 3
F = 2700 N

Step 2 :  Then use the work equation.

W = Fs
= 2700 × 100
= 270 000 J
= 270 kJ                     Ans.  270 kJ

In Unit 2 you will learn an even quicker way to solve this type of problem.

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