Question

A woman at mass 80kg lifts a bricks of mass 20kg up a vertical ladder of width 2m width length 6m. What is the work done?

Answer 1

Here we'll assume that the woman lifted the brick slowly.

That'd mean that she applied a force just equal to the gravitational force acting on the brick.

Gravitational force by earth acting on an object is given by

F = mg

where, m is the mass of object and g is the acceleration due to gravity (which is equal to 9.8 ms-²)

Here, mass of brick is 20 kg

So force by gravity (Fg) would be

Fg = 20 × 9.8 = 196N (unit of force is Newton, N)

Now the woman would apply the same force upwards

Fw = 196 N (upwards)

Fw is the force applied by woman.

Now work done is equal to Force × displacement

Here, Force = Fw = 196 N

displacement = 6 m

So work done by woman = 196 × 6

= 1176 N