Question

a man mass 50 kg is standing in an elevator . if elevator is moving up with an acceleration g/3 then work done by normal reaction of floor of elevator on man when elevator moves by a distance 12 m is

Answer 1

A man of mass 50kg is standing in an elevator.

so, weight of man = mg = 50kg × 10m/s² = 500N

elevator is moving up with an acceleration g/3.

so, Psuedo force acting downward.

i.e., Psuedo force, P = mg/3 = 500/3 N

so, net force acting downward direction, F = Weight of body + Psuedo force

= 500 + 500/3 = 2000/3 N

at equilibrium,

upward force = downward force

or, normal reaction = net force , F

or, normal reaction = 2000/3 N

we know,

workdone = force × displacement

so, workdone by normal reaction = normal reaction × displacement

= 2000/3 × 12 = 8000J