When jogging at 13 km/h on a level surface, a 70-kg man uses energy at a rate of approximately 850 W. Using the facts that the "human engine" is approximately 25% efficient, determine the rate at which this man uses energy when jogging up a 5.0° slope at this same speed. Assume that the frictional retarding force is the same in both cases.
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- A 83kg teacher (including the mass of his gear) hikes up a mountain! During his hike he experiences a 5N drag (and negligible friction impeding her motion). The distance of the path and the height of the mountain are shown. List the energy types at the initial and final time and whether work and loss (due to non- conservative forces) occur as well as the corresponding amounts of energy. initial: none 940m work? work loss? loss 7300m final: GPE How many calories did he burn if his body does work with 22% efficiency? reference level Hint: Divide the work by the efficiency (in decimal form), then convert to Calories. Calories (also known as kilocalories) check answers cannot be determinec energy, complete problems 3 Scientific Online CalculatorWhat is the efficiency of an out-of-condition professor who does 2.30 ✕ 105 J of useful work while metabolizing 490 kcal of food energy?% (b) How many food calories would a well-conditioned athlete metabolize in doing the same work with an efficiency of 15%?(a) How high a hill can a car coast up (engine disengaged) if friction is negligible and its initial speed is 74.0 km/h? _______ 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 9.0 m above its starting point, how much thermal energy was generated by friction? ________ J (c) What is the average force of friction if the hill has a slope 2.5° above the horizontal? ________ N (down the slope)
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- Which of the following statements are true about mechanical energy? Include all that apply. The total amount of mechanical energy of an object is the sum of its potential energy and the kinetic energy. Heat is a form of mechanical energy. The mechanical energy of an object is always conserved. When non-conservative forces do work, energy is transformed from kinetic to potential (or vice versa), but the total mechanical energy is conserved. A bowling ball is mounted from a ceiling by way of a strong cable. It is drawn back and released, allowed to swing as a pendulum. As it swings from its highest position to its lowest position, the total mechanical energy is mostly conserved. When a friction force does work on an object , the total mechanical energy of that object is changed. The total mechanical energy of an object remains constant if the only forces doing work on the object are conservative forces. If an object gains mechanical energy, then one can be certain that a…A 2.00 kg block is released from rest on a ramp that is inclined at an angle of 60.0∘∘ below the horizontal. The initial position of the block is a vertical distance of 2.00 mm above the bottom of the ramp. If the speed of the block is 4.00 m/sm/s when it reaches the bottom of the ramp, what was the work done on it by the friction force? What is the unit of measure?A 7.80-g bullet moving at 690 m/s penetrates a tree trunk to a depth of 5.10 cm. (a) Use work and energy considerations to find the average frictional force that stops the bullet.N(b) Assuming the frictional force is constant, determine how much time elapses between the moment the bullet enters the tree and the moment it stops moving.s
- A 2.28 kg block is pushed 1.69 m up a ver- tical wall with constant speed by a constant force of magnitude F applied at an angle of 60.8° with the horizontal. The acceleration of gravity is 9.8 m/s². 60.8° F 2.28 kg If the coefficient of kinetic friction between the block and wall is 0.631, find the work done by F. Answer in units of J. Answer in units of J. Your response... i Previous Responses X #1.37.76 PALETTEMs. Dewitte's son, Theo, slides down a slide, from rest, with a length of 2.00 m at an incline of 50° above the horizontal. He has a mass of 22.0 kg and he reaches the bottom of the slide with a velocity of 2.90 m/s. Briefly explain if total mechanical energy was conserved and what energy transfers otcurred?Melinda is pushing a chair along a 5 meter straight path through her living room. She is standing, pushing at the top of the chair with a force of 30 newtons at a 22° angle of depression from the horizontal. (a) Calculate the work done in moving the chair. (b) How could Melinda re-arrange herself to make the energy use more efficient?