#38 A ball is attached to one end of a wire, the other end being fastened to the
ID: 1774538 • Letter: #
Question
#38 A ball is attached to one end of a wire, the other end being fastened to the ceiling. The wire is held horizonta initially at rest on a horizontal frictionless al, and the ball is released from rest (see the drawing). It swings downward and strikes a block surface. Air resistance is negligible, and the collision is elastic. The masses of the ball and block are, respectively. 1.60 kg and 2.40 kg, and the length of the wire is 1.20 m. Find the velocity (magnitude and direction) of the ball (a) just before the collision, and (b) just after the collision. .20m Li V-t/29h t/2(4.si)Qan.) v: 23.544 mls The velocity besore collision 23.SHmis belore coExplanation / Answer
a) initial PE = final PE
m g h = 1/2 m v2
v = sqrt [2 * g * h] = sqrt [2 * 9.8 * 1.2]
v = 4.85 m/s
positive x direction
b)From conservation of linear momentum
vf = [ m1 - m2 / m1 + m2 ] * v
= [ 1.6 - 2.4 / 1.6 + 2.4 ] * 4.85
vf = -0.97 m/s
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