Question

4) A child pulls a toy car through a distance of 10 metres on a smooth, horizontal floor. The
String held in child's hand makes an angle of 60° with the horizontal surface. The force
applied by the child be 5N.
D) If the string makes 90° angle,calculate the work done by child in pulling toy car?​

Answer 1

Explanation:

if the string makes a 90° with 5N

horizontal component will be 5cos90°

and sadly cos90 is zero

therefore Workdone also become zero

these are the steps

W = f×d

= 5cos90 × 10

= 0

BUT

if the string makes 90°with 5N vertically

therefore in this case we have a workdone

horizontal component is 5N

therefore

w=fd

5×10

50W (if the string makes an angle 90° to the vertical direction)...

EXTRA

WORKDONE BY CHILD IF CHILD HAND MAKES

AN ANGLE 60° TO THE HORIZONTAL

first of all we have to get the horizontal component

therefore we get 5cos60° as our h-component

so the workdone is

W = F×d

= 5cos60 × 10

= 25W