Trick question
The collision was ELASTIC!!!
Therefore the energy after is the energy before and it is all kinetic.
Therefore:
If the moving ball stops, the formerly still ball goes on at the original speed.
A) 3.5 m/s
B) ZERO. The first ball was NOT moving before the collision.
The TRANSLATIONAL Ke of the moving ball is (1/2) (.4) (3.5)^2
This ignores the rotational Ke of a rolling ball. It is (1/2) I w^2 where I is the moment of inertia and w is the angular velocity, which we do not know.
C) The second ball was at REST after the collision so again ZERO.
Two 0.4 kg soccer balls collide elastically in a head-on collision. The first ball starts at rest, and the second ball has a speed of 3.5 m/s. After the collision, the second ball is at rest.
A.) What is the final speed of the ball?
B.) What is the kinetic energy of the first ball before the collision?
C.) What is the Kinetic energy of the second ball after the collision?
1 answer