(a) How high (in m) a hill can a car coast up (engine disengaged) if friction is negligible and its initial speed is 74.0 km/h? (Enter a number.) x m (b) If, in actuality, a 750 kg car with an initial speed of 74.0 km/h is observed to coast up a hill to a height 10.0 m above its starting point, how much thermal energy (in )) was generated by friction? (Enter a number.) × J (c) What is the average force of friction (down the slope) if the hill has a slope 2.5° above the horizontal? (Enter your answer in N. Enter a number.) X N
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- Assuming the human body is 25% efficient, how much energy would be used by a 75 kg person climbing a set of stairs 15 m tall? Express the answer in both Joules and food calories, Cal.(a) How high (in m) a hill can a car coast up (engine disengaged) if friction is negligible and its initial speed is 76.0 km/h? (Enter a number.) 140.61 (b) If, in actuality, a 750 kg car with an initial speed of 76.0 km/h is observed to coast up a hill to a height 12.0 m above its starting point, how much thermal energy (in J) was generated by friction? (Enter a number.) 203256 (c) What is the average force of friction (down the slope) if the hill has a slope 2.5° above the horizontal? (Enter your answer in N. Enter a number.) 706.44 x N(a) How high (in m) a hill can a car coast up (engine disengaged) if friction is negligible and its initial speed is 102 km/h? (Enter a number.) m (b) If, in actuality, a 750 kg car with an initial speed of 102 km/h is observed to coast up a hill to a height 22.0 m above its starting point, how much thermal energy (in J) was generated by friction? (Enter a number.) (c) What is the average force of friction (down the slope) if the hill has a slope 2.5° above the horizontal? (Enter your answer in N. Enter a number.) N
- If, in actuality, a 750-kg car with an initial speed of 116 km/h is observed to coast up a hill and stops at a height 24.5 m above its starting point, how much thermal energy was generated by friction in J?(a) What is the efficiency of an out-of-condition professor who does 2.30 ✕ 105 J of useful work while metabolizing 510 kcal of food energy?(b) How many food calories would a well-conditioned athlete metabolize in doing the same work with an efficiency of 25%?A child on a swing is released from rest at an angle of 60º from vertical. At the low point (0º from vertical), the swing and child together are 2 meters below the bar that the swing is attached to. Neglecting friction, use the energy approach to find the speed of the child at the low point. b) Suppose the 25 kg child’s speed is actually 3 m/s at the low point. How much energy was lost (work done by nonconservative forces) in this process?
- What is the efficiency of an out-of-condition professor who does 1.90 ✕ 105 J of useful work while metabolizing 510 kcal of food energy? (Enter your answer as a percentage. Enter a number.)% How many food calories (in kcal) would a well-conditioned athlete metabolize in doing the same work with an efficiency of 25%? (Enter a number.)kcalA 27.0 kg child slides down a long slide in a playground. She starts from rest at a height h11 of 23.00 m. When she is partway down the slide, at a height h22 of 13.00 m, she is moving at a speed of 6.80 m/s.Calculate the mechanical energy lost due to friction (as heat, etc.).(a) If the car has the initial speed stated at a height of h = 0, how high, in meters, can the car coast up a hill if work done by friction is negligible? Part (b) If, in actuality, a 760-kg car with an initial speed of 108 km/h is observed to coast up a hill and stops at a height 23 m above its starting point, how much thermal energy was generated by friction in J? Part (c) What is the magnitude of the average force of friction, in newtons, if the hill has a slope 2.9° above the horizontal?
- Suppose that the average U.S. household uses 14100 kWh (kilowatt-hours) of energy in a year. If the average rate of energy consumed by the house was instead diverted to lift a 1690 kg car 15.8 m into the air, how long would it take? car: S Using the same rate of energy consumption, how long would it take to lift a loaded Boeing 747 airplane, with a mass of 3.90 x 10° kg, to a cruising altitude of 9.42 km? airplane: SAssume that the energy content in food can be converted to mechanical energy with 100% efficiency. How many chocolate candy bars (each with 330 kcal) would it take to climb Mount Everest (8850 m)? Assume that the mass of the climber, including equipment, is 127 kg. Round up to the nearest whole number.(1)An energy-efficient lightbulb, taking in 23.0 W of power, can produce the same level of brightness as a conventional lightbulb operating at power 100 W. The lifetime of the energy-efficient bulb is 10 000 h and its purchase price is $4.00, whereas the conventional bulb has lifetime 750 h and costs $0.46 per bulb. Determine the total savings obtained by using one energy-efficient bulb over its lifetime as opposed to using conventional bulbs over the same time period. Assume an energy cost of $0.20 per kilowatt-hour.$