COLLEGE PHYSICS
13th Edition
ISBN: 2810014673880
Author: OpenStax
Publisher: OpenStax
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Chapter 7, Problem 47PE
(a) What is the efficiency of an out-of-condition professor who does
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A block of mass m₁
=
10.0 kg is connected to a block of mass m₂
34.0 kg by a massless string that passes over a light, frictionless pulley. The 34.0-kg block is connected to a spring that has negligible mass and a force constant of k = 200 N/m as shown in the figure below. The spring is
unstretched when the system is as shown in the figure, and the incline is frictionless. The 10.0-kg block is pulled a distance h = 22.0 cm down the incline of angle = 40.0° and released from rest. Find the speed of each block when the spring is again unstretched.
Vm1
×
1.32
Vm2
= 1.32
×
m/s
m/s
A block of mass m₁ = 10.0 kg is connected to a block of mass m₂ = 34.0 kg by a massless string that passes over a light, frictionless pulley. The 34.0-kg block is connected to a spring that has negligible mass and a force constant of k = 200 N/m as shown in the figure below. The spring is
unstretched when the system is as shown in the figure, and the incline is frictionless. The 10.0-kg block is pulled a distance h = 22.0 cm down the incline of angle 0 = 40.0° and released from rest. Find the speed of each block when the spring is again unstretched.
m/s
Vm1
Vm2
m/s
mi
m2
k
i
Truck suspensions often have "helper springs" that engage at high loads. One such arrangement is a leaf spring with a helper coil spring mounted on the axle, as in the figure below. The helper spring engages when the main leaf spring is compressed by distance yo, and then helps to
support any additional load. Consider a leaf spring constant of 5.45 × 105 N/m, helper spring constant of 3.60 × 105 N/m, and y = 0.500 m.
Truck body
Dyo
Axle
(a) What is the compression of the leaf spring for a load of 4.90 × 105 N?
m
(b) How much work is done compressing the springs?
]
Chapter 7 Solutions
COLLEGE PHYSICS
Ch. 7 - Give an example of something think of as work in...Ch. 7 - Give an example of a situation in which there is a...Ch. 7 - Describe a situation in which a force is exerted...Ch. 7 - The person in Figure 7.33 does work on the lawn...Ch. 7 - Work done on a system puts energy into it Work...Ch. 7 - When solving for speed in Example 7.4, we kept...Ch. 7 - In Example 7.7, we calculated the final speed of a...Ch. 7 - Does the work you do on a book when you lift it...Ch. 7 - What is a conservative force?Ch. 7 - The force exerted by a diving board is...
Ch. 7 - Define mechanical energy. What is the relationship...Ch. 7 - What is the relationship of potential energy to...Ch. 7 - Consider the following scenario. A car for which...Ch. 7 - Describe the energy transfers and transformations...Ch. 7 - Do devices with efficiencies of less than one...Ch. 7 - List four different forms or types of energy. Give...Ch. 7 - List the energy conversions that occur when riding...Ch. 7 - Most electrical appliances are rated in watts....Ch. 7 - Explain, in terms of the definition of power, why...Ch. 7 - A spark of static electricity, such as that you...Ch. 7 - Explain why it is easier to climb a mountain on a...Ch. 7 - Do you do work on the outside world when you rub...Ch. 7 - Shivering is an involuntary response to lowered...Ch. 7 - Discuss the relative effectiveness of dieting and...Ch. 7 - What is the difference between energy conservation...Ch. 7 - If the efficiency of a coal-fired electrical...Ch. 7 - How much work does a supermarket checkout...Ch. 7 - A 75.0-kg person climbs stairs, gaining 2.50...Ch. 7 - (a) Calculate the work done on a 1500-kg elevator...Ch. 7 - Suppose a car travels 108 km at a speed of 30.0...Ch. 7 - Calculate the work done by an 85.0-kg man who...Ch. 7 - How much work is done by the boy pulling his...Ch. 7 - A shopper pushes a grocery cart 20.0 m at constant...Ch. 7 - Suppose the ski patrol lowers a rescue sled and...Ch. 7 - Compare the kinetic energy of a 20,000-kg truck...Ch. 7 - (a) How fast must a 3000-kg elephant move to have...Ch. 7 - Confirm the value given for the kinetic energy of...Ch. 7 - (a) Calculate the force needed to bring a 950-kg...Ch. 7 - A car's bumper is designed to withstand a 4.0-km/h...Ch. 7 - Boxing gloves are padded to lessen the force of a...Ch. 7 - Using energy considerations, calculate the average...Ch. 7 - A hydroelectric power facility (see Figure 7.38)...Ch. 7 - (a) How much gravitational potential energy...Ch. 7 - Suppose a 350-g kookaburra (a large kingfisher...Ch. 7 - In Example 7.7, we found that the speed of a...Ch. 7 - A 100-g toy car is propelled by a compressed...Ch. 7 - In a downhill ski race, surprisingly, little...Ch. 7 - A 5.00105 -kg subway train is brought to a stop...Ch. 7 - A pogo stick has a spring with a force constant of...Ch. 7 - A 60.0-kg skier with an initial speed of 12.0 m/s...Ch. 7 - (a) How high a hill can a car coast up (engine...Ch. 7 - Using values from Table 7.1, how many DNA...Ch. 7 - Using energy considerations and assuming...Ch. 7 - If the energy in fusion bombs were used to supply...Ch. 7 - (a) Use of hydrogen fusion to supply energy is a...Ch. 7 - The Crab Nebula (see Figure 7.41) pulsar is the...Ch. 7 - Suppose a star 1000 times brighter than our Sun...Ch. 7 - A person in good physical condition can put out...Ch. 7 - What is the cost of operating a 3.00-W electric...Ch. 7 - A large household air conditioner may consume 15.0...Ch. 7 - (a) What is the average power consumption in watts...Ch. 7 - (a) What is the average useful power output of a...Ch. 7 - A 500-kg dragster accelerates from rest to a final...Ch. 7 - (a) How long will it take an 850-kg car with a...Ch. 7 - (a) Find the useful power output of an elevator...Ch. 7 - (a) What is the available energy content, in...Ch. 7 - (a) How long would it takea 1.50105 -kg airplane...Ch. 7 - Calculate the power output needed for a 950-kg car...Ch. 7 - (a) Calculate the power per square meter reaching...Ch. 7 - (a) How long can you rapidly climb stairs...Ch. 7 - (a) What is the power output in watts and...Ch. 7 - Calculate the power output in watts and horsepower...Ch. 7 - (a) What is the efficiency of an out-of-condition...Ch. 7 - Energy that is not utilized for work or heat...Ch. 7 - Using data from Table 7.5, calculate the daily...Ch. 7 - What is the efficiency of a subject on a treadmill...Ch. 7 - Shoveling snow can be extremely taxing because the...Ch. 7 - Very large forces are produced in joints when a...Ch. 7 - Jogging on hard surfaces with insufficiently...Ch. 7 - (a) Calculate the energy in kJ used by a 55.0-kg...Ch. 7 - Kanellos Kanellopoulos flew 119 km from Crete to...Ch. 7 - The swimmer shown in Figure 7.44 exerts an average...Ch. 7 - Mountain climbers carry bottled oxygen when at...Ch. 7 - The awe-inspiring Great Pyramid of Cheops was...Ch. 7 - (a) How long can you play tennis on the 800 kJ...Ch. 7 - Integrated Concepts (a) Calculate the force the...Ch. 7 - Integrated Concepts A 75.0-kg cross-country skier...Ch. 7 - Integrated Concepts The 70.0-kg swimmer in Figure...Ch. 7 - Integrated Concepts A toy gun uses a spring with a...Ch. 7 - Integrated Concepts (a) What force must be...Ch. 7 - Unreasonable Results A car advertisement claims...Ch. 7 - Unreasonable Results Body fat is metabolized,...Ch. 7 - Construct Your Own Problem Consider a person...Ch. 7 - Construct Your Own Problem Consider humans...Ch. 7 - Integrated Concepts A 105-kg basketball player...
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Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, physics and related others by exploring similar questions and additional content below.Similar questions
- A skier of mass 75 kg is pulled up a slope by a motor-driven cable. (a) How much work is required to pull him 50 m up a 30° slope (assumed frictionless) at a constant speed of 2.8 m/s? KJ (b) What power (expressed in hp) must a motor have to perform this task? hparrow_forwardA block of mass 1.4 kg is attached to a horizontal spring that has a force constant 900 N/m as shown in the figure below. The spring is compressed 2.0 cm and is then released from rest. a x = 0 x b (a) A constant friction force of 4.4 N retards the block's motion from the moment it is released. Using an energy approach, find the position x of the block at which its speed is a maximum. cm (b) Explore the effect of an increased friction force of 13.0 N. At what position of the block does its maximum speed occur in this situation? cmarrow_forwardA block of mass m = 3.00 kg situated on a rough incline at an angle of 0 = 37.0° is connected to a spring of negligible mass having a spring constant of 100 N/m (see the figure below). The pulley is frictionelss. The block is released from rest when the spring is unstretched. The block moves 11.0 cm down the incline before coming to rest. Find the coefficient of kinetic friction between block and incline. k=100 N/m Ө marrow_forward
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