Question

A ball of mass 0.7 kg flies through the air at low speed, so that air resistance is negligible. (a) What is the net force acting on the ball while it is in motionWhich components of the ball's momentum will be changed by this force? What happens to the x component of the ball's momentum during its flight? What happens to the y component of the ball's momentum during its flight? It decreases. What happens to the z component of the ball's momentum during its flight?

Answer 1

Answer:

A) Gravitational Force, $F=-6.86N$.

B) The y component of momentum.

C) The x component of momentum will remain the same.

D)The y component of momentum decreases.

E)The z component of momentum will remain constant.

Explanation:

First, let the x-axis be positive in the same direction as the horizontal speed of the ball, let the y-axis be positive in the opposite direction of gravity.

A) since there is no air resistance, the only force acting on the ball is the gravitational force. This force is downwards so it is negative. The net force is

$F=-9.8*0.7=-6.86N$.

B)Because the net force (and the only one) is on the y-axis, only the vertical component of the momentum will be changed due to the force.

C)Since there is no resistance of air, the ball behaves as in projectile motion problems, this means that the x component of the velocity remains constant, also does the mass. Remembering that momentum is velocity times mass, it can be easily seen that x component of momentum remains constant too.

D)The y component of momentum decreases, this is because gravity decreases the y component of the velocity.

E)Since there is no z component of the force there is no change in the z component of the momentum.