Question

An elevator is moving down with a constant acceleration of 1 ms-2 . How lighter does an 80 kg man feel riding the elevator

Answer 1

answer : 80N

explanation : an elevator is moving down with a constant acceleration of 1m/s². hence, man inside the elevator is in non-inertial frame of reference. and we know, we can't apply Newton's law in non-inertial frame of reference to make it inertial frame, apply a force of same magnitude in just opposite in direction.

so, net force = weight of man (downward) + Psuedo force(upward)

= mg + m(-a)

= m(g - a)

= 80 × (10 - 1)

= 80 × 9 = 720N

hence, normal reaction acting on man = 720N

but the actual weight of man = mg = 80 × 10 = 800N

hence, 800 - 720 = 80N lighter does an 80kg man feel riding the elevator.