hi, i need help please, i have 2 questions i need their completesolutions 1) A 2

Question

hi,

i need help please, i have 2 questions i need their completesolutions



1)

A 20-kg object sitting at rest is struck elastically in a head-oncollision with a 10-kg object initially moving at +3.0 m/s. Findthe final velocity of the 20-kg object after the collision.



2)

A 7.0-kg bowling ball strikes a 2.0-kg pin. The pin flies forwardwith a velocity of 6.0 m/s; the ball continues forward at 4.0 m/s.What was the original velocity of the ball?



thanks in advance..

Explanation / Answer

(a) The final velocity of 20 kg object is                     v1f = [ 2 m2 * v2i / m1 + m2]                          = [ 2 * 10 * 3 / 20 + 10 ]                          = 2.0 m/s (b) According to conservation of momentum we have        m1 u1 = m1 v1 + m2v2 ==> u1 = [ m1 v1 + m2 v2 ] / m1               = [ 7 * 4 + 2 * 6] / 7               = 5.714 m/s

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