Question

Two bodies of different masses are dropped simultaneously from the top of a tower. If air resistance is proportional to the mass of the body. Then,

• A. The heavier body reaches the ground earlier
• B. The lighter body reaches the ground earlier
• C. Both the bodies reach the ground simultaneously
• D. Can not be decided

Answer 1

Answer: (C)

Both the bodies reach the ground simultaneously

If air resistance is proportional to mass of the body, then acceleration due to it will be independent of mass and hence the two bodies will reach ground simultaneously.

$a=\frac{mg-f_{air}}{m}=\frac{mg-m\alpha }{m}=g-\alpha$.

This acceleration is independent of mass and hence same time will be required.