Name______
CP Practice with Work
1. A roller coaster must do work raising its cars to the highest point on the ride. From there, the cars coast at varying speed until they return to the starting point. Suppose a loaded roller coaster car must be pulled 157 m from the ride’s starting point to the top of the first rise. If 2130000 J of work must be done on the car during this stage of the ride, how large is the force exerted on the car by the raising mechanism?
2. A sunken treasure has a mass of 2140 kg, most of which is due to silver and gold coins. In order to make it easier to raise the treasure, a diver descends 17 m to where the treasure is located and attaches balloon-like bladders to each corner of the treasure chest. The diver then inflates these bladders, so they provide buoyancy to the chest. The chest is still too heavy to float upward, but its weight has been largely counteracted by the inflated bladders, so that now it can be easily lifted by 4270 J of net work. What is the magnitude of the net force that is exerted on the treasure in order to raise it to the water’s surface?
3. A girl pulls a wagon along a level path for a distance of 15.0 m. The handle of the wagon makes an angle of 20° with the horizontal, and the girl exerts a force of 35.0 N on the handle. Friction provides a force of 24.0 N. Find the net work that is done on the wagon.
4. The longest shish kebab ever made was 881.0 m long. Suppose the meat and vegetables need to be delivered in a cart from one end of this shish kebab’s skewer to the other end. A cook pulls the cart by applying a force of 40.00 N at an angle of 45.00° above the horizontal. If the force of friction acting on the cart is 28.00 N, what is the net work done on the cart and its contents during the delivery?
5. The world’s largest flag, which was manufactured in Pennsylvania, has a length of 154 m and a width of 78 m. The flag’s mass is 1240 kg, which may explain why the flag has never been flown from a flagpole. Suppose this flag is being pulled by two forces: a force of 8000 N to the east and a force of 5000 N that is directed 30.0° south of east. How much work is done in moving the flag 20.0 m directly south?
6. If the stairs of the Sears Tower in Chicago, Illinois, can be climbed by an athlete with a power output of 331 W, how long does it take the athlete to climb the building’s 442 m height? Assume the athlete has a mass of 55 kg and that all of the power goes toward doing work against gravity.
7. When it is completed in 2002, the International Financial Center in Taipei, Taiwan, will be the tallest building in the world. The International Financial Center will also have the fastest elevators in the world. Two of the 63 elevators will travel from the ground floor to the eighty-ninth floor in just 39 s. Suppose the power output of each elevator motor is 158 kW. How much work will these motors do in lifting the elevator to the eighty-ninth floor?
8. The space shuttle, which was first launched on April 12, 1981, is the world’s first reusable space vehicle. The shuttle is placed in orbit by three engines that do J of work in 8.5 min. What is the power output of these engines?
9. Elliot Schmuckduck is pushing a refrigerator up an incline that is 6 m long and 3 m high. The refrigerator is 990 kg.
A. What is the work done by Elliot on the refrigerator?
B. Assuming that his applied force on the refrigerator is parallel to the incline, what is the applied force?
C. What is the total work done by Elliot?
10. The lift hill on Steel Force is 61.7 m high and 144 m long. The train is 6000 kg.
A. What is the work done by the chain motor?
B. What is the applied force of the chain on the train?
C. If the train takes 39 sec to reach the top of the hill, what is the power output of the chain motor?