Explain why momentum of a billiard ball rolling on billiard table changes.?

Question

Explain why momentum of a billiard ball rolling on billiard table changes.?

Answer 1

too many beers.

Answer 2

inertia wants the ball to keep rolling at a constant speed, while friction between the ball and the table and the ball and air (drag) slow it down.

Answer 3

Hi,

If you are asking what i think you are asking then there are several answers. Could be table is not level. Could be that cloth is dirty or bad. Table may not have been set up right. Cue ball or ball rolling may be damaged. Any one of these things and couple others could lead to ball not rolling true.

Thank You

Answer 4

its all to do with friction

Answer 5

In short, friction, like everyone else has said.  More technically, it can be explained as follows:

Momentum = mass * velocity

The mass of the ball is not changing, so only a change in the velocity will change the momentum.  If the velocity changes, it means the ball is accelerating (negative acceleration is decelerating).  Also, we know that:

Force = mass * acceleration  or acceleration = force / mass

Again, the mass of the ball is not changing, but there are forces acting on the ball, namely a frictional force between the ball and the cloth (equal to the normal force of the ball on the cloth multiplied by the coefficient of static friction).  There will also be a small amount of drag from the air resistance.

So, since there is a frictional force which opposes the motion of the ball, there will be a negative acceleration, which causes the velocity to decrease, which changes the momentum.

Also, if the ball hits a cushion, the collision is not purely elastic, as some energy will be absorbed by the cushion, so the ball does not rebound at the same speed at which it hits the cushion, also changing the velocity.

Answer 6

one word... friction.  If it wasnt for that, it would go on endlessly.  Once the energy of the cue ball is transferred to the first ball it hits, its carries that momentum and the only thing that slows it down is friction and continues till friction brings it to a stop.