Question

Determine work done by a person if he slowly lights a block of mess ‘m’ through a vertical
height ‘h’ and then walks horizontally a distance ‘d’ while holding the block

Answer 1

When the person lifts the block of mass m slowly to a height h,
force = mg
displacement (in the direction of force) = h
work done = force × displacement
                = mgh
                
When he walks horizontally a distance d while holding the block,
displacement = d
force = mg (perpendicular to displacement)
so work done = 0

So total work done = mgh + 0 = mgh