Concepts Of Physics MCQ Edition [Volume 1]PhysicsSome Mechanical Properties of Matter
When falling in air, a solid sphere reaches a terminal velocity of 20 m/s . If it is instead allowed to fall in a vacuum,
Options
- Athe terminal velocity will be 20 m/s
- Bthe terminal velocity will be more than 20 m/s
- Cthere will be no terminal velocity
- Dthe terminal velocity will be less than 20 m/s
Correct answer
C. there will be no terminal velocity
Step-by-step solution
Terminal velocity is the constant velocity attained by a falling body when the net force acting on it becomes zero. This happens when the downward gravitational force is balanced by the upward viscous drag and buoyant forces. In a vacuum, there is no fluid to provide viscous drag or buoyant force. The only force acting on the sphere is its weight, which causes a constant downward acceleration equal to the acceleration due to gravity ( g ). Since the sphere continuously accelerates under gravity, its velocity keeps