question_answer

A lead shot of a 1mm diameter falls through a long column of glycerine. The variation of its velocity v with distance covered is represented by:

A)

B)                

C)

D)  

Correct Answer: A

Solution :

Key Idea: After travelling certain distance the net force on lead shot is zero. The velocity of falling lead shot goes on increasing due to the effective force acting downward on the ball. The layer of glycerin in contact with lead shot tends to move with a velocity velocity of lead shot, a stage is finally increasing reached when the velocity opposing viscous force becomes equal to the effective force driving the ball. The net force on the shot is now zero and lead shot attain a constant velocity called the terminal velocity.