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Chapter 4 Work and Energy Tutorial Questions
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Chapter 4 Work and Energy Tutorial Questions
Due: 11:00am on Tuesday, June 11, 2013
Note: To understand how points are awarded, read your instructor's Grading Policy.
Work from a Constant Force
Description: Compute the work …show more content…
Maximum weight
Hill’s law states that there exists a maximum force that a muscle can exert, and thus a maximum weight that a muscle can lift. Only one graph has a limit to the maximum force that can be produced.
ANSWER:
A
B
C
D
E
Part B
The powerexerted by a muscle is the product of the force exerted and the velocity of contraction. The area of which of these shaded regions represents the power exerted while a weight is lifted at maximum speed?
Hint 1. How to approach the problem
In this example, power is the product of the force exerted by the muscles and the contraction velocity of the muscles. In lifting any given weight, our muscles have a single maximum contracting velocity; we assume, in this case, that the weight is lifted at this velocity.
In lifting a given weight at a constant velocity, your muscles exert a constant force. Therefore, in this example, both the force and the contraction velocity are constant for a given weight. How can the product of two constant numbers be shown graphically?
ANSWER:
A
B
C
D
None of the above
6/5/2013 1:34 PM
MasteringPhysics: Print View with Answers
10 of 22 …show more content…
Notice that if you lift a very large weight (near the limit of the maximum force your muscle can produce), the area of this "long and skinny" rectangle can be quite small. If you lift a very small weight, the area of this "tall and skinny" rectangle can also be quite small. However, if you lift a weight near the middle of your weightlifting range, the area of the rectangle, and hence the power produced by your muscle, is a maximum.
Energy Required to Lift a Heavy Box
Description: Find force needed to lift a box with a single pulley. Then compare energy needed to lift box directly, versus with a pulley.
As you are trying to move a heavy box of mass
, you realize that it is too heavy for you to lift by yourself. There is no one around to help, so you
attach an ideal pulley to the box and a massless rope to the ceiling, which you wrap around the pulley. You pull up on the rope to lift the box.
Use
for the magnitude of the acceleration due to gravity and neglect friction forces.
Part A
What is the
1 of 22
http://session.masteringphysics.com/myct/assignmentPrintView?assignm...
Signed in as Johnny Chung Yin Ho, Instructor
AP1201
Sign Out
( AP1201S2013C01 )
My Courses
Course Settings
Course Home
University Physics with Modern Physics, 13e
Young/Freedman
Assignments
Roster
Gradebook
Item Library
Chapter 4 Work and Energy Tutorial Questions
Overview
Help
Summary View
Diagnostics View
Instructor Resources
eText
Study Area
[ Edit ]
Print View with Answers
Chapter 4 Work and Energy Tutorial Questions
Due: 11:00am on Tuesday, June 11, 2013
Note: To understand how points are awarded, read your instructor's Grading Policy.
Work from a Constant Force
Description: Compute the work …show more content…
Maximum weight
Hill’s law states that there exists a maximum force that a muscle can exert, and thus a maximum weight that a muscle can lift. Only one graph has a limit to the maximum force that can be produced.
ANSWER:
A
B
C
D
E
Part B
The powerexerted by a muscle is the product of the force exerted and the velocity of contraction. The area of which of these shaded regions represents the power exerted while a weight is lifted at maximum speed?
Hint 1. How to approach the problem
In this example, power is the product of the force exerted by the muscles and the contraction velocity of the muscles. In lifting any given weight, our muscles have a single maximum contracting velocity; we assume, in this case, that the weight is lifted at this velocity.
In lifting a given weight at a constant velocity, your muscles exert a constant force. Therefore, in this example, both the force and the contraction velocity are constant for a given weight. How can the product of two constant numbers be shown graphically?
ANSWER:
A
B
C
D
None of the above
6/5/2013 1:34 PM
MasteringPhysics: Print View with Answers
10 of 22 …show more content…
Notice that if you lift a very large weight (near the limit of the maximum force your muscle can produce), the area of this "long and skinny" rectangle can be quite small. If you lift a very small weight, the area of this "tall and skinny" rectangle can also be quite small. However, if you lift a weight near the middle of your weightlifting range, the area of the rectangle, and hence the power produced by your muscle, is a maximum.
Energy Required to Lift a Heavy Box
Description: Find force needed to lift a box with a single pulley. Then compare energy needed to lift box directly, versus with a pulley.
As you are trying to move a heavy box of mass
, you realize that it is too heavy for you to lift by yourself. There is no one around to help, so you
attach an ideal pulley to the box and a massless rope to the ceiling, which you wrap around the pulley. You pull up on the rope to lift the box.
Use
for the magnitude of the acceleration due to gravity and neglect friction forces.
Part A
What is the