Question

A man in the lift weighs more, when the lift is

• A. Accelerating upwards
• B. Moving up with constant velocity
• C. Accelerating downwards
• D. Moving down with constant velocity

Answer 1

The correct option is A

Accelerating upwards

Weight:

1. The weight of a person can be defined as the force that is exerted by the person on Earth's surface.
2. This force or weight is the product of the mass of the person and acceleration due to gravity $W=mg$.

Explanation for Correct Option:

Option A is correct.

1. When the lift is accelerating upwards, its acceleration will be -a, which will be added to the acceleration due to gravity to calculate the resultant acceleration.
2. Therefore, the weight is $W=m\left(g-\left(-a\right)\right)=m\left(g+a\right)$, due to which the person feels heavier.

Explanation for Incorrect Options:

Option B:

Moving up with constant velocity: As the velocity is constant, there will be no acceleration of the lift and therefore, the weight of the man will remain the same.

Option C:

Accelerating downwards: When the lift is accelerating upwards, its acceleration will be a, which will be added to the acceleration due to gravity to calculate the resultant acceleration. Therefore, the weight is $W=m\left(g-a\right)$, due to which the person feels heavier.

Option D:

Moving down with constant velocity: As the velocity is constant, there will be no acceleration of the lift and therefore, the weight of the man will remain the same.

Hence, the correct option is option A.