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1. The figure below shows an approximate representation of the contact force ver

ID: 2259807 • Letter: 1

Question

1.

The figure below shows an approximate representation of the contact force versus time during the collision of a 75 g tennis ball with a wall.  The initial velocity of the ball is 7.140

The figure below shows an approximate representation of the contact force versus time during the collision of a 75 g tennis ball with a wall. The initial velocity of the ball is 7.140 times 101 m/s, in the positive x direction, perpendicular to the wall. What is the impulse, J, that the wall exerts on the ball? What is the speed of the tennis ball after the collision?

Explanation / Answer

1)
impulse = area under the curve

impulse = 0.5*2*10^-3*1200 + (9-2)*10^-3*1200 + 0.5*1*10^-3*1200


impulse = 10.2 N.s

2) impulse = change inmomentum

10.2= m*(v2-v1)

10.2=75*10^-3 *(v2 -(- 71.4)

v2 = (10.2 - 71.3*75*10^-3)/(75*10^-3) = 64.7 ( in the opposite direction)