Question

1. Define work. Give its S.I unit. Write an expression for positive work done.

2. Calculate the work done in pushing a cart through a distance of 50 m against the force of friction equal to 250 N. Also state the type of work done.

3. What will be the work done, if displacement of the object is perpendicular to the directions of force.

4. When person moves on a circular path and reached to the same point from where he starts, then what will be the work done?

Answer 1

1. Work is said to be done when the force applied on an object produces a displacement in the object in the direction of force applied.
   Work = Force x displacement (positive work)
   S.I unit of work done = Joule.
2. We are given that
   Force (F) = 250 N, displacement (s) = 50 w
   ∴ Work done = F x S
   = 250 x 50
   = 1250 Joule
   Here, work done is negative.
3. The work done by force is zero.
4. The work done is also zero here because there is no displacement.