/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Q22 DQ In example 10.10 (Section 10.6) ... [FREE SOLUTION] | 91影视

91影视

Log out

Learning Materials

Features

Discover

Chapter 1: Q22 DQ (page 328)

In example 10.10 (Section 10.6) the rotational kinetic energy of the professor and dumbbells increases. But since there are no external torques, no work is being done to change the rotational kinetic energy. Then, by Eq. (10.22), the kinetic energy must remain the same! Explain what is wrong with this reasoning which leads to an apparent contradiction. Where does the extra kinetic energy come from?

Short Answer

Expert verified

There is no contradiction because the work is done.

Step by step solution

01

Reference used

A physics professor stands at the center of a frictionless turntable with arms outstretched and a 5 kg dumbbell in each hand. He is set rotating about the vertical axis, making one revolution is 2 s.

02

Explanation

The work is done here.

The increase in kinetic energy comes from the positive work that the professor performs in pulling his arms and weighing toward the center.

The force and displacement are in the same direction, so the system鈥檚 kinetic energy increases.

03

Conclusion

Hence, there is no contradiction, kinetic energy increases because the work is done.

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Over 30 million students worldwide already upgrade their learning with 91影视!

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

A Tennis Serve. In the fastest measured tennis serve, the ball left the racquet at 73.14m/s. A served tennis ball is typically in contact with the racquet for30.0and starts from rest. Assume constant acceleration. (a) What was the ball鈥檚 acceleration during this serve? (b) How far did the ball travel during the serve?

Given two vectorsA鈫�=鈭�2.00i^+3.00j^+4.00k^andB鈫�=3.00i^+1.00j^鈭�3.00k^, (a) find the magnitude of each vector; (b) use unit vectors to write an expression for the vector differenceA鈫�鈭�B鈫�; and (c) find the magnitude of the vector differenceA鈫�鈭�B鈫�. Is this the same as the magnitude ofB鈫�鈭�A鈫�? Explain.

A cylindrical bucket, open at the top, is 25.0 cm high and 10.0 cm in diameter. A circular hole with a cross-sectional area 1.50 cm2 is cut in the center of the bottom of the bucket. Water flows into the bucket from a tube above it at the rate of 2.40 x 10-4m3/s. How high will the water in the bucket rise?

A small rock is thrown vertically upward with a speed of22.0 m/s from the edge of the roof of a 30.0-m-tall building. Therock doesn鈥檛 hit the building on its way back down and lands onthe street below. Ignore air resistance. (a) What is the speed of therock just before it hits the street? (b) How much time elapses fromwhen the rock is thrown until it hits the street?

For a spherical planet with mass M, volume V, and radius R,derive an expression for the acceleration due to gravity at the planet鈥檚 surface, g, in terms of the average density of the planet, 蚁=M/V, and the planet鈥檚 diameter, D=2R. The table gives the values of Dand gfor the eight major planets:

(a) Treat the planets as spheres. Your equation for as a function of and shows that if the average density of the planets is constant, a graph of versus will be well represented by a straight line. Graph as a function of for the eight major planets. What does the graph tell you about the variation in average density? (b) Calculate the average density for each major planet. List the planets in order of decreasing density, and give the calculated average density of each. (c) The earth is not a uniform sphere and has greater density near its center. It is reasonable to assume this might be true for the other planets. Discuss the effect this nonuniformity has on your analysis. (d) If Saturn had the same average density as the earth, what would be the value of at Saturn鈥檚 surface?
See all solutions

Recommended explanations on Physics Textbooks

Mechanics and Materials

Read Explanation

Scientific Method Physics

Read Explanation

Energy Physics

Read Explanation

Physics of Motion

Read Explanation

Particle Model of Matter

Read Explanation

Dynamics

Read Explanation
View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.