Essential Cosmic Perspective
9th Edition
ISBN: 9780135795033
Author: Bennett
Publisher: PEARSON
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Chapter 4, Problem 39EAP
Perpetual Motion Machines. Every so often, someone claims to have built a machine that can generate energy perpetually from nothing. Why isn’t this possible according to the known laws of nature? Why do you think claims of perpetual motion machines sometimes receive substantial media attention?
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13. You learned in Science that Energy is conserved,
that Potential Energy must balance Kinetic energy.
Mathematically, that means:
1
mgh =-mv², where mgh is Potential
%3D
Energy
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and -mv² is Kinetic energy. Reminder that m is
2
mass, g is the acceleration due to gravity, h is
height and v is velocity.
a) Balance this equation such that the sum of
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the negative at the end!) Show your work!
+
tv
MAR
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Instruction: Read and understand this lesson. Write your answer in a long bond paper/yellow
раper.
Problem Solving:
A. Gravitational Potential Energy
1) Climbing a vertical rope is difficult. You have to lift your full body weight with your arms.
If your mass is 60 kg and you climb 2.0 m, by how much do you increase your
gravitational potential energy?
2) Ten days after it was launched toward Mars in December 1998, the Mars Climote
Orbiter spacecraft (mass 629 kg) was 2.87 x 10 km from the earth and traveling at
1.20 x 10 km/h relative to the earth. At this time, what were:
a) The spacecraft's kinetic energy relative to the earth and
b) The potential energy of the earth-spacecraft system?
A 20 Newton weight is lifted to a height of 5 meters above the ground. As a result, the weight has a gravitational potential energy of 100 Joules. If the weight were to drop, what would be the kinetic energy of the weight just before it hits the ground (you can assume there is no air resistance)?
A.) 0 Joules
B.) 20 Joules
C.) 50 Joules
D.) 100 Joules
Chapter 4 Solutions
Essential Cosmic Perspective
Ch. 4 - Prob. 1VSCCh. 4 - Check your understanding of some of the many types...Ch. 4 - Check your understanding of some of the many types...Ch. 4 - Check your understanding of some of the many types...Ch. 4 - Check your understanding of some of the many types...Ch. 4 - Define speed, velocity, and acceleration. What are...Ch. 4 - Define momentum and force. What do we mean when we...Ch. 4 - What is free-fall, and why does it make you...Ch. 4 - Prob. 4EAPCh. 4 - Prob. 5EAP
Ch. 4 - Define kinetic energy, radiative energy, and...Ch. 4 - Define and distinguish temperature and thermal...Ch. 4 - Prob. 8EAPCh. 4 - Summarize the universal law of gravitation both in...Ch. 4 - What is the difference between a bound and an...Ch. 4 - Under what conditions can we use Newton’s version...Ch. 4 - Explain why orbits cannot change spontaneously,...Ch. 4 - Explain how the Moon creates tides on Earth. Why...Ch. 4 - How do the tides vary with the phase of the Moon?...Ch. 4 - Decide whether the statement makes sense (or is...Ch. 4 - Decide whether the statement makes sense (or is...Ch. 4 - Decide whether the statement makes sense (or is...Ch. 4 - Decide whether the statement makes sense (or is...Ch. 4 - Decide whether the statement makes sense (or is...Ch. 4 - Decide whether the statement makes sense (or is...Ch. 4 - Decide whether the statement makes sense (or is...Ch. 4 - Decide whether the statement makes sense (or is...Ch. 4 - Decide whether the statement makes sense (or is...Ch. 4 - Decide whether the statement makes sense (or is...Ch. 4 - A car is accelerating when it is (a) traveling on...Ch. 4 - Compared to their values on Earth, on another...Ch. 4 - Which person is weightless? (a) a child in the air...Ch. 4 - Consider the statement “There’s no gravity in...Ch. 4 - To make a rocket turn left, you need to (a) fire...Ch. 4 - Compared to its angular momentum when it is...Ch. 4 - Prob. 31EAPCh. 4 - If Earth were twice as far from the Sun, the force...Ch. 4 - According to the law of universal gravitation,...Ch. 4 - If the Moon were closer to Earth, high tides would...Ch. 4 - Prob. 35EAPCh. 4 - Testing Gravity. Scientists are constantly trying...Ch. 4 - How Does the Table Know? Thinking deeply about...Ch. 4 - Perpetual Motion Machines. Every so often, someone...Ch. 4 - Group Activity: Your Ultimate Energy Source. Work...Ch. 4 - Weightlessness. Astronauts are weightless when in...Ch. 4 - Einstein’s Famous Formula. a. What is the meaning...Ch. 4 - The Gravitational Law. a. How does quadrupling the...Ch. 4 - Prob. 44EAPCh. 4 - Head to Foot Tides. You and Earth attract each...Ch. 4 - Space Elevator. Some people have proposed using a...Ch. 4 - Prob. 47EAPCh. 4 - Prob. 48EAPCh. 4 - Prob. 49EAPCh. 4 - Prob. 50EAP
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