Question

A Body Of Mass 32 Kg Is Suspended By A Spring Balance From The Roof of a vertically operating lift and going downward from rest. At the instants the lift has covered 20m and 50m, the spring balance showed 30kg and 36kg respectively. Then the velocity of the lift is: A) decreasing at 20m20m and increasing at 50m50m
B) increasing at 20m20m and decreasing at 50m50m
C) continuously decreasing at a steady rate throughout the journey
D) constantly increasing at constant rate throughout the journey.

Answer 1

Explanation:

According to Fbd

We know that,

N=m(g−a)

So, if N<mg

It is a case of downward acceleration

Then, the velocity is increase

Again, if N>mg

It is a case of downward retardation

Then, the velocity is decreases

Hence, the velocity is increasing at 20 m and decreasing at 50 m