(1)

Drag force can be calculated using the stokes law :

Where is the coefficient of viscosity of the air, is the radius of the sphere and is the velocity of the sphere. \ \

For beach ball and bowling ball .

Drag force on beach ball is .

Drag force on bowling ball is .

Thus, the drag force on beach ball is 2 times the drag force on the bowling ball.

Option (a) is correct.

(2)

Object reaches the terminal velocity when the net force on the object is to be zero.

Thus, .

This happens when the force of gravity and the drag froces are equal.

Drag force is .

Force due to gravity is .

When the object reaches the terminal velocity, then

Observe the expression, depends on value. \ \

Since the bowling ball has the maximum value, it will have largest terminal velocity. \ \

Option (c) is correct.

Drag force is related to velocity of the sphere. \ \

\ \

Experiment of throwing different spherical balls from certian height:

Ignore the air resistance, hence the drag resistance due to air is not considered.

For a freely falling body, the net force acting on the body is equal to the force due to gravity.

Hence each and every ball moves with same acceleration, that is, accerleration due to the gravity.

Since the balls are dropped from same height and move with same acceleration, they hit the ground at same time.

Hence all the balls will hit at same time.

Option (c) is correct choice.

(2)

Experiment of throwing different spherical balls from certian height:

The drag force due to air is considered.

The net force acting on the body: