1. Calculate the power required to lift the piano from the ground to that positi

Question

1. Calculate the power required to lift the piano from the ground to that position in exactly 27 seconds.

2. Calculate the net impulse delivered to a 138-kg quarterback initally running at 4.5 m/s if he's hit by a defending player and slowed to a speed of 1.1 m/s (still going in the same direction)

3. A 2.0 kg cart rolls to the right at a speed of 8.0 m/s and hits a stationary 5.0 kg cart. After they collide, the 2.0 kg cart is traveling to the left at a speed of 3.0 m/s. Calculate the final speed of the 5.0 kg cart.

4. Starting from rest a wheel accelerates at a rate of 9.2 rad/s^2 for 5.61 s. Calculate the number of revolutions it makes in this time.

Explanation / Answer

the position is not given.let the position is x m from ground.

then power=change in potential energy/time=m*g*x/27

where m=mass of piano

g=9.8 m/s^2

2)impulse=change in momentum=mass*change in veloicty=138*(4.5-1.1)=469.2 Kg.m/s

3)conserving momentum,

2*8=2*(-3)+5*v

v=22/5=4.4 m/s,to the right

4)number of rad=0.5*9.2*5.61^2=144.77 rad

number of revolutions=144.77/(2*pi)=23.04

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