2. A 2000 kg car accelereates from rest under the actions of two forces. One is a forward foce of 1140 N provided by traction between the wheels and the road. The other is a 950 N resistive force due to various frictional forces. Use the work-kinetic energy theorem( Net work=change in kinetic energy) to determine how far the car must travel for its speed to reach 2.0m/s .
3. A 2100 kg car starts from rest at the top of a driveway that is sloped at an angle of 20.0 degree with the horizontal. An average friction force of 4000N impedes the car's motion so that the car's speed at the bottom of the driveway is 3.8 m/s. What is the length of the driveway?
4. A 75kg bobsled is pushed along a horizontal surface by two athletes. After the bobsled is pushed a distance of 4.5 m starting from rest, its speed is 6.0 m/s. Find the magnitude of the net force on the bobsled.
5. A 40kg child is in a swing that is attached to ropes 2 m long. Find the gracitational potential energy associated with the child relative to the child's lowest postion inder the following conditions:
a. when the ropes make a 30 degre angle with the vertical
b. at the bottom of the circular arc
6. A bird is flying with a sped of 18m/s over water when it drops a 2kg fish. If the altitude of the bird is 5.4m and friction is disregarded, what is the speed of the fish when it hits the water?
7. A 755N diver drops from a board 10 m above the water's surface. Find the diver's speed 5 m above the water's surface. Then find the diver's speed just before striking the water.
8. If the diver in item 2 leaves the board with an initial upward speed of 2m/s, find the diver's speed when striking the water.
9. An runner leaps over a hurdle. If the runner's initial vertical speed is 2.2m/s, how much will the runner's center of mass be raised during the jump?
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?
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