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1)A ball of mass 180 g is released from rest at a height of 2.50 m above the flo

ID: 1629570 • Letter: 1

Question

1)A ball of mass 180 g is released from rest at a height of 2.50 m above the floor and it rebounds straight up to a height of 0.700 m .part c) If the contact time with the floor was 0.0750 s , what was the average force the floor exerted on the ball? i cant get the answer i have tried 25.7, 68 N and 82 N

2)A 20 g bullet moving horizontally at 400 m/s penetrates a 3.1 kg wood block resting on a horizontal surface.(Figure 1) part A)If the bullet slows down to 300 m/s after emerging from the block, what is the speed of the block immediately after the bullet emerges?

After Before 400 m/sI 300 m/s

Explanation / Answer

1.) Force = Rate of change of momentum

mass of ball = 0.18 kg;

Velocity just before hitting the floor = 7m/s; by conservation of energy

velocity after hitting the ground = 3.70 m/s

Force =[ 0.18(7+3.70)] / 0.075

Force = 25.68 N

2)

The block has consumed 100 m/s velocity of bullet.

if bullet had been fred with 100 m/s it would have come to rest within

applying the law of conservation of energy

the lose in kinetic energy of bullet will lead t gain in velocity of the block

0.5x0.02(70,000) = 0.5x3.12xV^2

V = 21.18 m/s Answer