Question

A person of 72 kg wt. is standing on a weightmachine in a lift. If the lift falls freelywill be reading of weighing machine-(1) 72 kg, wt(2) 54 kg.m(3) 90 kg, wt (4) Zero​

Answer 1

Answer:-

$\boxed{\boxed{Zero}}$

Explanation:-

• When lift is stationary the weight equal to mg.

I.e. W = mg.

• When lift is moving upward with acceleration 'a' .The weight of the person increases.

So,apparent weight is

Apparent Weight = m(g + a).

• When lift is moving downwards with acceleration 'a' .The weight of the person decreases.

So,apparent weight is

Apparent Weight = m(g - a).

• When there is free fall the acceleration equals the acceleration due to gravity.

I.e. a = g.

Now, Apparent Weight becomes

Apparent Weight = m(g - g)

Apparent Weight = 0.

This the case of weightlessness.

$\boxed{\boxed{Apparent Weight = 0}}$

So,the weighing machine will show zero Kg-wt.