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Edit View History Bookmarks Window Help @ 16% [h} Mon 10:04 PM Mastering Physlcs-2017 Fall General Physics H Problem 741 s previous ] 1 Problem 7.41 Part B A 144-g baseball moving 28 m/s strikes a stationary 5.25-kg brick resting on small rollers so t moves without significant friction After hitting the brick, the baseball bounces straight back, and the brick moves forward at 1.17 m/s Delermine the total kinelic energy before the colision Express your answer to two significant figures and include the appropriate units My Answers Give Up Part C Determine the total kinetic energy ater the collision Express your answer to two significant figures and include the appropriate units KEValue Units My Answers Give Up S0, 999

Explanation / Answer

(a) Let the velocity of the ball after collision is v m/s, By the law of momentum conservation:-
=>m1u1+m2u2 = m1v1 + m2v2
=>0.144 x 28 + 5.25 x 0 = 0.144 x v + 5.25 x 1.17
=>v = - 14.65 m/s {-ve just indicating the direction}
(b) KE(initial) = 1/2m1u1^2 = 1/2 x 0.144 x (28)^2 = 56.45 J
&

KE(final) = 1/2m1v1^2 + 1/2m2v2^2
=>KE(final) = 1/2 x 0.144 x (14.65)^2 + 1/2 x 5.25 x (1.17)^2
=>KE(final) = 19.04 J

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