1. | because there is very little friction, the lever is an extremely efficient simple machine. Using a 90.0-percent-efficient lever, what input work is required to lift an 18.0-kg mass through a distance of 0.50 m? |
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2. | Two people carry identical 40 N boxes up a ramp. The ramp is 2.0 m long and rests on a platfrom that is 1.0 m high. One person walks up the ramp is 2.0s, and the other person walks up the ramp in 4.0s. What is the difference in power the two people use to carry the boxes up the ramp? |
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3. | The ramp in Figure 10-23 is 18 m long and 4.5 m high Figure 10-23 What force, parallel to the ramp (FA), is required to slide a 25-kg box at constant speed to the top of the ramp if friction is disregarded? |
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4. | The box in the diagram is being pushed up the ramp with a force of 100 N. If te height of the ramp is 3.0 m, what is the work done on the box? |
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5. | A compound machine used to raise heavy boxes consists of a ramp and a pulley. The efficiency of pulling a 100 kg box up the ramp is 50%. If the efficiency of the pulley is 90%, what is the overall efficiency of the compound machine? |
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6. | A pulley system consits of two fixed pulleys and two movable pullys that lift a load that has a weight of 300 N. If the effort force used to lift the load is 100 N, What is the mechnaical advantage of the system? |
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7. | A skater is a mass of 50 kg slides across an icy pond with negligible friction. As he approaches a frienD, both he and his friend hold out their hands, and the friend exerts a force in the direction opposite to the skater's movement, which slows the skater's speed from 2.0 m/s^{2} to 1.0 m/s^{2}. What is the change in the skater's kinetic energy? |
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8. | The diagram shows a box being pulled by a rope with a force of 200N along a horizontal suface. The angle the rope makes with the horizontal is 45o. Calculate the work doen on the box and the power required to pull it a distance of 5.0 m in 10s. |
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9. | A 4N soccer ball sits motionless on a field. A player's foot exerts a force of 5N on the ball for a distance of 0.1 m, and the ball rolls a distance of 10m. How much kinetic energy does the ball gain from the player? |
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10. | A A 20 N block is attached to the end of a rope and the rope is looped around a pulley system. If you pull the opposite end of the rope a distance of 2.0 m, the pulley system raises the block a distance of 0.40 m. What is the pulley system's ideal mechanical advantage? |
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