Question

Ball X of mass 1.0 kg and ball Y of mass 0.5kg travel toward each other on a horizontal surface. Both balls travel with a constant speed of 5 m/s until they collide. During the collision, ball Y exerts an average force with a magnitude of 40N for 1/6s on ball X . Which of the following best predicts ball momentum after the collision?
A. Ball Y will travel at a speed less than 5 m/s in the same direction of travel as before the collision.
B. Ball Y will travel at a speed less than 5 m/s in the opposite direction of travel as before the collision.
C. Ball will travel at a speed greater than 5 m/s in the same direction of travel as before the collision.
D. Ball Y motion cannot be predicted because the impulse on it is not known.

Answer 1

Answer:

C

Explanation:

Ball Y will travel at a speed greater than 5 m/s in the opposite direction of travel as before the collision.

Answer 2

Answer:

B. Ball Y will travel at a speed less than 5 m/s in the opposite direction of travel as before the collision.

Explanation:

Impulse created by ball Y  on ball X = 40 x 1/6 Ns

Ball X will also create impulse 40 / 6 on ball Y .

impulse = change in momentum .

impulse in Y = change in momentum in Y .

Initial momentum of Y  = .5 x 5 = 2.5

Let final velocity of Y after collision be v  in opposite direction .

change in momentum of Y = v - (-2.5 )

so,

v + 2.5 = 40 / 6 =  6.67

v =  4.17 m / s .

Option B is correct .

B. Ball Y will travel at a speed less than 5 m/s in the opposite direction of travel as before the collision.