We will first draw the diagram for this problem. The toy car is moving along horizontal floor, so we draw a horizontal line OX to show the direction of motion of the toy car (see Figure 12). Now, the force of 5 N is applied along the string tied to the toy car making an angle of `60^(@)` with the floor. So, we draw another line OA making an angle of `60^(@)` with horizontal floor OX. In Figure 12 OX represents the direction of motion and OA represents the direction of force, the angle between them being `60^(@)` . Now, we know that the formula for work done when a body moves at an angle to the direction of force is :
`W = F cos theta xx s`
Here, Force, F = 5 N
Angle, `theta = 60^(@)`
And, Distance, s = 10 m
So, putting these values in the above formula, we get :
Work done, `W = 5 xx cos 60^(@) xx 10`
Now, if we look up the table of natural cosines, we will find that `cos 60^(@) = 0.5`. So putting this value of `cos 60^(@)` in the above relation, we get :
`W = 5 xx 0.5 xx 10`
= 25 J
Thus, the work done is 25 joules.
