6. A 145-g baseball moving 30.5 m/s strikes a stationary 5.75-kg brick resting on small rollers so it moves without significant friction. After hitting the brick, the baseball bounces straight back, and the brick moves forward at 1.10 m/s. a. What is the baseball's speed after the collision? (10pts) b. Find the total kinetic energy before the collision. (10pts) c. Find the total kinetic energy after the collision. (10pts)

a)

momentum of baseball before collision

mass x velocity

=.145 x 30.5

= 4.4225 kg m / s

momentum of brick after collision

= 5.75 x 1.1

= 6.325 kg m/s

Applying conservation of momentum

4.4225 + 0 =.145 x v + 6.325, v is velocity of baseball after collision.

v = - 13.12 m / s

b)

kinetic energy of baseball before collision = 1/2 mv²

=.5 x. 145 x 30.5²

= 67.44 J

Total kinetic energy before collision = 67.44 J

c)

kinetic energy of baseball after collision = 1/2 x. 145 x 13.12²

= 12.48 J.

kinetic energy of brick after collision

=.5 x 5.75 x 1.1²

= 3.48 J

Total kinetic energy after collision

= 15.96 J