Please
10. 11. . Give an example of something we think of as work in everyday circumstances that is not work in the scientic sense. Is energy transferred or changed in form in your example? If so, explain how this is accomplished without doing work. . A body moves in a circle at constant speed. Does the centripetal force that accelerates the body do any work? Explain. . How much work does a supermarket checkout attendant do on a can of soup he pushes 0.600 m horizontally with a force of 5.00 N? . A shopper pushes a grocery cart 20.0 m at constant speed on level ground, against a 35.0 N frictional force. He pushes in a direction 250" below the horizontal. (a) What is the work done on the cart by friction? (b) What is the work done on the cart by the gravitational force? (c) What is the work done on the cart by the shopper? (d) Find the force the shopper exerts, using energy considerations. (e) What is the total work done on the cart? . Suppose the ski patrol lowers a. rescue sled and victim, having a total mass of 90.0 kg, down a 60.0\" slope at constant speed, as shown to the right. The coefficient of friction between the sled and the snow is 0.100. (a) How much work is done by friction as the sled moves 30.0 in along the hill? (b) How much work is done by the rope on the sled in this distance? (c) What is the work done by the gravitational force on the sled? (d) What is the total work done? . Calculate the kinetic energies of (a) a 2000 kg automobile moving at 100 km/h; (b) an 80 kg runner sprinting at 10 m/s; and (c) a 9.1 x 10'31 kg electron moving at 2.0 x 107 m/s. . An 8.0 g bullet has a speed of 800 m/s. (8.) What is its kinetic energy? (b) What is its kinetic energy if the speed is halved? (a) Calculate the force needed to bring a 950 kg car to rest from a speed of 90.0 km/ h in a. distance of 120 m (a fairly typical distance for a non-panic stop). (b) Suppose instead the car hits a concrete abutment at full speed and is brought to a stop in 2.00 m. Calculate the force exerted on the car and compare it with the force found in part (a). A constant 10 N horizontal force is applied to a 20 kg cart at rest on a level oor. If friction is negligible, what is the speed of the cart when it has been pushed 8.0 In? A 7.0 kg box slides along a horizontal frictionless oor at 1.7 m/s and collides with a relatively massless spring that compresses 23 cm before the box comes to a stop. (a) How much kinetic energy does the box have before it collides with the spring? (b) Calculate the work done by the spring. (0) Determine the spring constant of the spring. A small block of mass 200 g starts at rest at A, slides to B where its speed is 1.13 = 8.0 m/s, then slides along the horizontal surface a distance 10 on before coming to rest at C. (See below.) (a) What is the work of friction along the curved surface? (b) What is the coefcient of kinetic friction along the horizontal surface? A T 4.0 m l B c I-10rn-l 12. A sled starts from rest at the top of a snowcovered incline that makes a 22 angle with the horizontal. After sliding 75 111 down the slope, its speed is 14 m/s. Use the work-energy theorem to calculate the coefcient of kinetic friction between the runners of the sled and the snowy surface
