A fully loaded, slow-moving freight elevator has a cab with a total mass of 1500 kg, which is required to travel upward 45 m in 1.1 min, starting and ending at rest. The elevator's counterweight has a mass of only 920 kg, so the elevator motor must help pull the cab upward. What average power is required of the force the motor exerts on the cab via the cable? Number Units

A fully loaded, slow-moving freight elevator has a cab with a total mass of 1500 kg, which is required to travel upward 45 m in 1.1 min, starting and ending at rest. The elevator's counterweight has a mass of only 920 kg, so the elevator motor must help pull the cab upward. What average power is required of the force the motor exerts on the cab via the cable? Number Units

College Physics

10th Edition

ISBN:9781285737027

Author:Raymond A. Serway, Chris Vuille

Publisher:Raymond A. Serway, Chris Vuille

Chapter5: Energy

Section: Chapter Questions

Problem 20CQ: A car accelerates uniformly from rest. Ignoring air friction, when does the car require the greatest...

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Review. The mass of a car is 1 500 kg. The shape of the cars body is such that its aerodynamic drag coefficient is D = 0.330 and its frontal area is 2.50 m2. Assuming the drag force is proportional to v2 and ignoring other sources of friction, calculate the power required to maintain a speed of 100 km/h as the car climbs a long hill sloping at 3.20.
A car accelerates uniformly from rest. Ignoring air friction, when does the car require the greatest power? (a) When the car first accelerates from rest, (b) just as the car reaches its maximum speed, (c) when the car reaches half its maximum speed. (d) The question is misleading because the power required is constant. (e) More information is needed.
A car accelerates uniformly from rest. Ignoring air friction, when does the car require the greatest power? (a) When the car first accelerates from rest, (b) just as the car reaches its maximum speed, (c) when the car reaches half its maximum speed. (d) The question is misleading because the power required is constant. (e) More information is needed.
Give an example of a situation in which there is a force and a displacement, but the force does no work. Explain why it does no work.
A worker pushes a wheelbarrow with a horizontal force of 50 N on level ground over a distance of 5.0 m. 11 a friction force of 43 N acts on the wheelbarrow in a direction opposite that of the worker, what work is done on the wheelbarrow by the worker? (a) 250 J (b) 215 (c) 35 J (d) 10 J (e) None of those answers is correct.
The system shown in Figure P5.43 is used to lift an object of mass m = 76.0 kg. A constant downward force of magnitude F is applied to the loose end of the rope such that the hanging object moves upward at constant speed. Neglecting the masses of the rope and pulleys, find (a) the required value of F, (b) the tensions T1, T2, and T3, and (c) the work done by the applied force in raising the object a distance of 1.80 m. Figure P5.43
A particle is subject to a force Fx that varies with position as shown in Figure P7.9. Find the work done by the force on the particle as it moves (a) from x = 0 to x = 5.00 m, (b) from x = 5.00 m to x = 10.0 m, and (c) from x = 10.0 m to x = 15.0 m. (d) What is the total work done by the force over the distance x = 0 to x = 15.0 m?
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A 1.50 103-kg car starts from rest and accelerates uniformly to 18.0 m/s in 12.0 s. Assume that, air resistance remains constant at 4.00 102 N during this time. Find (a) the average power developed by the engine and (b) the instantaneous power output of the engine at t = 12.0 s, just before the car stops accelerating.
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. A particular hydraulic pile driver uses a ram with a mass of 1040 kg. If the maximum pile energy is 11,780J, how high must the ram he raised to achieve this value? Assuming it takes 0.62 s for the pile driver’s winch motor to raise the ram at a constant speed to this height, what is the power output by the motor in completing this task? Express your answer in both watts and horsepower.
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