1. The third floor of a house is 10 m above the street level. How much work is required to lift a 500 kg refrigerator to the third story level?
1. The third floor of a house is 10 m above the street level. How much work is required to lift a 500 kg refrigerator to the third story level?
2. (a) How much work is done when you push a crate horizontally with 150 N across a 20 m school floor?
(b) If the
(c) How many joules of energy will be turned into heat?
3. A car moving at 60 km/h skids 20 m with locked brakes. How far will the car skid with locked brakes at 120 km/h?
4. In raising a 6000 N piano with a pulley system, the workers note that for every 3 m of rope pulled downward, the piano raises 0.3 m. What is the force required to lift the piano?
5. How many watts of power do you expend when you exert a force of 3 N that moves a book 5 m in a time interval of 2 seconds?
6. Jane holds an apple of mass m over the edge of a bridge of height h = 9m. She drops the apple and it falls to the river bellow. What will be the speed of the apple when it hits the river?
7. A 60 Kg woman is attached to a bungee cord with an unstretched length of 12m. She jumps off a tower; from a height of 70 m. When she finally stops, the cord has a stretched length of 37m. Assuming the spring constant of the bungee cord is 69.8 N/m, what is the total potential energy relative to the ground when the woman stops falling?
8. A 534 N boy drops from a diving platform 12 m above the water. Find the boy's speed 4m above the water's surface. Then find his speed just before hitting the water.
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