Phy need help 20 point----2

10. A pendulum bob is released from some initial height such that the speed of the bob at the bottom of the swing is 1.9m/s. What is the initial height of the bob?

11. A 1000kg elevator carries a max. load of 800kg. A constant frictional force of 4000N retards the elevator's motion upward. What min. power, in kW, must the motor deliver to lift the fully loaded elevator at a constant speed of 3m/s?

12. A car with a mass of 1500kg starts form rest and accelerates to a speed of 18m/s in 20s. Assume that the force of resistance remains constant at 400N during this time . What is the average power developed by the car's engine?

13. How long does it take a 19kW steam engine to do 6.8x10^7 J of work?

14. A 1500 kg car accelerates uniformly from rest to 10 m/s in 3 s.
a. What is the work done on the car in this time interval?
b. What is the power delivered by the engine in this time interval?

http://www.sendspace.com/file/1z0t4s
From 19-25, 33-36