HELP! A 1.0 kilogram rubber ball traveling east at 4.0 meters per second hits a

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wall and bounces back toward..? the west at 2.0 meters per second. What is the kinetic energy of the ball after it bounces off the wall compared to the kinetic energy of the ball before it hits the wall?

a. the same
b. four times as great
c. one-fourth as great
d. one-half as great

PLEASE SHOW ME THE MATH STEPS!! Thanks =]
 
the kinetic energy is defined as 1/2 mv^2
initially,
KE0 = 1/2 (1)(4)^2 =8J
final
KEf = 1/2 (1)(2)^2 = 2J

divide
KEf/KE0 = 2/8 = 1/4 answer
letter c
 
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