- Albert is pulling a 25.0-kg block up a hill which has an angle of ? = 15.50. H

Question

- Albert is pulling a 25.0-kg block up a hill which has an angle of ? = 15.50. He pulls it at a constant velocity a total distance of 2.75 m. Assuming there is no friction, calculate the work done by each force listed and the total work done on the block.

-On a horizontal table, a spring is attached to allow only horizontal compression, as shown here. If the spring is compressed 5.00 cm and then released, the 1.50-kg block accelerates from rest to a maximum speed of 3.50 m/s. What is the spring constant of this spring? (Ignore any friction.)

-A pitcher throws a 2.50-kg softball towards a batter with an initial speed of 20.0 m/s. If the batter hits the ball straight back to the pitcher with an average force of 57500 N for a time of 3.00 ms, what is the velocity of the softball?

Explanation / Answer

1) W = m*g*L*sin15.5 = 25*9.8*2.75*sin15.5 = 180.05 J

2) Vmax = A*w

w = 3.5/0.05 = 70 rad/s

k = m*w^2 = 1.5*70*70 = 7350 N/m

3) F = m*(vf-vi)/t

Vf = (F*t)/m + Vi

Vf = (57500*0.003)/2.5 + 20

Vf = 89 m/s

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