Concepts Of Physics MCQ Edition [Volume 1]
- Exam
- Concepts Of Physics MCQ Edition [Volume 1]
- Subject
- Physics
- Chapter
- Some Mechanical Properties of Matter
Concepts Of Physics MCQ Edition [Volume 1] · Physics · Some Mechanical Properties of Matter
A raindrop descending near the surface of the earth maintains an...
A raindrop descending near the surface of the earth maintains an almost uniform velocity because
Options
- Athe surface tension force balances its weight
- Bits weight is negligible
- Cthe viscous force of the air balances its weight
- Dthe atmospheric electric field balances the weight of the charged drops
Correct answer
C. the viscous force of the air balances its weight
Step-by-step solution
When a raindrop falls under gravity, it accelerates initially. As its velocity increases, the upward viscous drag force exerted by the air also increases.
According to Stokes' law, the viscous force is directly proportional to the velocity of the raindrop ().
When this upward viscous force becomes equal to the downward weight of the raindrop, the net force acting on it becomes zero.
As a result, the raindrop stops accelerating and continues to fall with a constant velocity, known as the terminal velocity.
According to Stokes' law, the viscous force is directly proportional to the velocity of the raindrop ().
When this upward viscous force becomes equal to the downward weight of the raindrop, the net force acting on it becomes zero.
As a result, the raindrop stops accelerating and continues to fall with a constant velocity, known as the terminal velocity.