Q23. A pulley system consists of six identical pulleys arranged in two groups of three as shown below. What is the mechanical advantage of the system? Q24. The pulley in the question above is used to lift a mass of 500 kg through a height of 2.5 m. Ignoring friction, determine (a) The force applied to the free end of the rope (b) The maximum tension at any point in the rope (c) The work done Q25. In the question above, it is found that in reality a force of 1000 N must be applied to lift the mass. Why is this? What is (a) the efficiency of the system and (b) the actual work done in lifting the mass? What becomes of the additional energy expended?

Q23. A pulley system consists of six identical pulleys arranged in two groups of three as shown below. What is the mechanical advantage of the system? Q24. The pulley in the question above is used to lift a mass of 500 kg through a height of 2.5 m. Ignoring friction, determine (a) The force applied to the free end of the rope (b) The maximum tension at any point in the rope (c) The work done Q25. In the question above, it is found that in reality a force of 1000 N must be applied to lift the mass. Why is this? What is (a) the efficiency of the system and (b) the actual work done in lifting the mass? What becomes of the additional energy expended?

College Physics

1st Edition

ISBN:9781938168000

Author:Paul Peter Urone, Roger Hinrichs

Publisher:Paul Peter Urone, Roger Hinrichs

Chapter7: Work, Energy, And Energy Resources

Section: Chapter Questions

Problem 64PE: Integrated Concepts (a) What force must be supplied by an elevator cable to produce an acceleration...

See similar textbooks

Similar questions

A person in good physical condition can put out 100 W of useful power for several hours at a stretch, perhaps by pedaling a mechanism that drives an electric generator. Neglecting any problems of generator efficiency and practical considerations such as resting time: (a) How many people ‘would it take to nm a 4.O0-kW electric clothes dryer? (b) How many people would it take to replace a large electric power plant that generates 800 MW?
Answer yes or no to each of the following questions. (a) Can an objectEarth system have kinetic energy and not gravitational potential energy? (b) Can it have gravitational potential energy and not kinetic energy? (c) Can it have both types of energy at the same moment? (d) Can it have neither?
(a) How long will it take an 850-kg car with a useful power output of 40.0 hp (1hp=746W) to reach a speed of 15.0 m/s, neglecting friction? (b) How long will this acceleration take if the car also climbs a 3.00-m-high hill in the process?
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 3.00-kg object has a velocity (6.00i1.00j)m/s. (a) What is its kinetic energy at this moment? (b) What is the net work done on the object if its velocity changes to (8.00i+4.00j)m/s. (Note: From the definition of the dot product, v2=vv.)
The Flybar high-tech pogo stick is advertised as being capable of launching jumpers up to 6 ft. The ad says that the minimum weight of a jumper is 120 lb and the maximum weight is 250 lb. It also says that the pogo stick uses a patented system of elastometric rubber springs that provides up to 1200 lbs of thrust, something common helical spring sticks simply cannot achieve (rubber has 10 times the energy storing capability of steel). a. Use Figure P8.32 to estimate the maximum compression of the pogo sticks spring. Include the uncertainty in your estimate. b. What is the effective spring constant of the elastometric rubber springs? Comment on the claim that rubber has 10 times the energy-storing capability of steel. c. Check the ads claim that the maximum height a jumper can achieve is 6 ft.
Integrated Concepts (a) What force must be supplied by an elevator cable to produce an acceleration of 0.800 m/s2 against a 200-N frictional force, if the mass of the loaded elevator is 1500 kg? (b) How much work is done by the cable in lifting the elevator 20.0 m? (c) What is the final speed of the elevator if it starts from rest? (d) How much work went into thermal energy?
. 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.
A block of mass m = 2.50 kg is pushed a distance d = 2.20 m along a frictionless, horizontal table by a constant applied force of magnitude F = 16.0 N directed at ail angle = 25 below the horizontal as shown in Figure P7.5. Determine the work done on the block by (a) the applied force, (b) the normal force exerted by the table, (c) the gravitational force, and (d) the net force on the block.
An 8.0-g bullet has a speed of 800 m/s. (a) What is its kinetic energy? (b) What is its kinetic energy if the speed is halved?
Integrated Concepts (a) Calculate the force the woman in Figure 7.46 exerts to do a push-up at constant speed, taking all data to be known to three digits. (b) How much work does she do if her center of mass rises 0.240 m? (c) What is her useful power output if she does 25 push-ups in 1 min? (Should work done lowering her body be included? See the discussion of useful work in Work, Energy, and Power in Humans. Figure 7.46 Forces involved in doing push-ups. The woman's weight acts as a force exerted downward on her center of gravity (CG).
A 500-kg dragster accelerates from rest to a final speed of 110 m/s in 400 m (about a quarter of a mile) and encounters an average frictional force of 1200 N. What is its average power output in watts and horsepower if this takes 7.30s?