T1a5p - H = 61 m 42 A 25.0-kg child on a 2.00-m-long swing...

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Assignment 5 Problems(Fall Term Physics 102) 13. A 70-kg base runner begins his slide into second base when moving at a speed of 4.0 m/s. The coefficient of friction between his clothes and Earth is 0.70. He slides so that his speed is zero just as he reaches the base. (a) How much mechanical energy is lost due to friction acting on the runner? (b) How far does he slide? KE = 560 J, D = 1.2 m 25. A 40-N toy is placed in a light swing that is attached to ropes 2.0 m long. Find the gravitational potential energy associated with the toy relative to its lowest position (a) when the ropes are horizontal, (b) when the ropes make a 30° angle with the vertical, and (c) at the bottom of the circular arc. PE a = 80 J, PE b = 11 J, PE c = 0 J 34. A projectile is launched with a speed of 40 m/s at an angle of 60° above the horizontal. Find the maximum height reached by the projectile during its flight by using conservation of energy.
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Unformatted text preview: H = 61 m 42. A 25.0-kg child on a 2.00-m-long swing is released from rest when the ropes of the swing make an angle of 30.0° with the vertical. (a) Neglecting friction, find the child’s speed at the lowest position. (b) If the actual speed of the child at the lowest position is 2.00 m/s, what is the mechanical energy lost due to friction? V=2.29 m/s, KE = 15.6 J 46. In a circus performance, a monkey is strapped to a sled and both are given an initial speed of 4.0 m/s up a 20° inclined track. The combined mass of monkey and sled is 20 kg, and the coefficient of kinetic friction between sled and incline is 0.20. How far up the incline do the monkey and sled move? D = 1.5 m 49. A 50.0-kg student climbs a 5.00-m-long rope and stops at the top. (a) What must her average speed be in order to match the power output of a 200-W light bulb? (b) How much work does she do? V=0.408 m/s, W = 2.45 KJ...
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