Question

If a man of mass 50 kg is in a lift moving down with a acceleration equal to acceleration due to gravity, then the apparent weight of the man is: 

• A. 0
• B. 100 N
• C. 25 N
• D. 5 N

Answer 1

The Correct Option is A

To solve the problem, we need to determine the apparent weight of a man in a lift that is accelerating downward with an acceleration equal to gravity.

1. Understanding Apparent Weight:
Apparent weight is the normal force exerted by the floor on the person. It is given by the equation:
$ W_{\text{apparent}} = m(g - a) $
where:
$m$ = mass of the man = 50 kg,
$g$ = acceleration due to gravity = 9.8 m/s²,
$a$ = acceleration of the lift = 9.8 m/s² (since it's moving down with acceleration equal to gravity).

2. Substituting the Values:
$ W_{\text{apparent}} = 50 \cdot (9.8 - 9.8) = 50 \cdot 0 = 0 \, \text{N} $

3. Interpretation:
When the lift moves downward with acceleration equal to gravity, the person experiences weightlessness because the normal force becomes zero. This is similar to free fall.

Final Answer:
The apparent weight of the man is 0 N.

Answer 2

The correct option is: (A) 0.

With the provided mass of the boy being m = 50 kg, and as the boy moves downward with an acceleration a = 9.8 m/s², the apparent weight (W_app) can be calculated as:

Apparent Weight = m * (g - a) = 50 * (9.8 - 9.8) = 50 * 0 = 0.