Work And Energy

Work, Energy, and Power
1. What is the work done by a force of 20 N acting through a parallel distance of 8 m? What force will do the same workthrough a distance of 4 m?

2. A trunk is dragged a horizontal distance of 24 m by a rope that makes an angle of 300 with the floor. If therope tension is 8 N, what work is done?

3. A rope making an angle of 350 drags a 10-kg toolbox a horizontal distance of 20 m. The tension inthe rope is 60 N and the constant friction force is 30 N. What work is done by the rope? What work is done by friction? What is the resultant work?4. What is the change in kinetic energy when a 50-g ball hits the pavement with a velocity of 16 m/s and rebounds with a velocity of 10 m/s?5. What average force is needed to increase the velocity of a 2-kg object from 5 m/s to 12 m/s over a distance of 8 m?

6. A 1500-kg car ismoving along a level road at 60 km/h. What work is required to stop the car? If k = 0.7, what is the stopping distance?

7. A 2-kg block rests ontop of a table 80 cm from the floor. Find the potential energy of the book relative to (a) the floor, (b) the seat of a chair 40 cm from thefloor, and (c) relative to the ceiling 3 m from the floor?

8. A 1.2 kg brick is held a distance of 2 m above a manhole. The bottom of the manholeis 3 m below the street. Relative to the street, what is the potential energy at each location? What is the change in potential energy?