Exercise 11 - Physics and Astronomy at TAMUpeople.physics.tamu.edu/mahapatra/teaching/ch11_mp_sols.pdf · Exercise 11.7 Description: Two ... drawbridge has been raised to an angle

11/14/2016 MasteringPhysics: Print View with Answers

https://session.masteringphysics.com/myct/assignmentPrintView?assignmentID=4714829 1/13

Chapter 11Due: 11:59pm on Sunday, November 13, 2016

To understand how points are awarded, read the Grading Policy for this assignment.

Exercise 11.7Description: Two people carry a heavy electric motor by placing it on a light board l long. One person lifts at one end witha force of F_1, and the other lifts the opposite end with a force of F_2. (a) What is the weight of the motor? (b) Wherealong the board...

Two people carry a heavy electric motor by placing it on a light board 1.50 long. One person lifts at one end with a force of440 , and the other lifts the opposite end with a force of 640 .

Part A

What is the weight of the motor?

ANSWER:

Part B

Where along the board is its center of gravity located?

ANSWER:

Part C

Suppose the board is not light but weighs 220 , with its center of gravity at its center, and the two people each exert thesame forces as before. What is the weight of the motor in this case?

ANSWER:

Part D

Where is its center of gravity located?

ANSWER:

Chapter 11 [ Edit ]

Overview Summary View Diagnostics View Print View with Answers

mN N

= = 1080 w N

= = 0.889 from the end where the 440 force is applied x m N

N

= = 860 w N

https://session.masteringphysics.com/myct/assignmentCreate?assignmentID=4714829

https://session.masteringphysics.com/myct/assignmentHome?assignmentID=4714829

https://session.masteringphysics.com/myct/assignmentStats?assignmentID=4714829

https://session.masteringphysics.com/myct/diagnostics?assignmentID=4714829

https://session.masteringphysics.com/myct/assignmentPrintView?assignmentID=4714829



Exercise 11.9Description: A wN, uniform, lm bar is suspended horizontally by two vertical cables at each end. Cable A can support amaximum tension of T_A without breaking, and cable B can support up to T_B. You want to place a small weight on thisbar. (a) What is the...

A 367 , uniform, 1.54 bar is suspended horizontally by two vertical cables at each end. Cable A can support a maximumtension of 497.0 without breaking, and cable B can support up to 442.0 . You want to place a small weight on this bar.

Part A

What is the heaviest weight you can put on without breaking either cable?

ANSWER:

Part B

Where should you put this weight?

ANSWER:

Exercise 11.11Description: A diving board of length 3.00 m is supported at a point 1.00 m from the end, and a diver weighing w_1stands at the free end . The diving board is of uniform cross section and weighs w_2. (a) Find the magnitude of the forceat the support point. (...

A diving board of length 3.00 is supported at a point 1.00 from the end, and a diver weighing 550 stands at the freeend . The diving board is of uniform cross section and weighs 270 .

= = 0.924 from the end where the 440 force is applied x m N

N mN N

= = 572 w N

= = 0.696 from the cable A d m

m m NN



Part A

Find the magnitude of the force at the support point.

ANSWER:

Part B

Find the direction of the force at the support point.

ANSWER:

Part C

Find the magnitude of the force at the lefthand end.

ANSWER:

Part D

Find the direction of the force at the lefthand end.

ANSWER:

= = 2060 F N

upward downward

= = 1240 F N



Exercise 11.13Description: In each case let w be the weight of the suspended crate full of priceless art objects. The strut is uniform andalso has weight w. (a) Find the tension T in the cable in the arrangement (a). (b) Find the magnitude of the force exertedon the...

In each case let be the weight of the suspended crate full ofpriceless art objects. The strut is uniform and also has weight .

Part A

Find the tension in the cable in the arrangement (a).

Express your answer in terms of .

ANSWER:

Part B

Find the magnitude of the force exerted on the strut by the pivot in the arrangement (a).


ANSWER:

Part C

Find the direction of the force exerted on the strut by the pivot in the arrangement (a).

ANSWER:

upward downward

ww

T

w

= T

w

= F



Part D

Find the tension in the cable in the arrangement (b).


ANSWER:

Part E

Find the magnitude of the force exerted on the strut by the pivot in the arrangement (b).


ANSWER:

Part F

Find the direction of the force exerted on the strut by the pivot in the arrangement (b).

ANSWER:

Exercise 11.14Description: The horizontal beam in weighs 190 N, and its center of gravity is at its center. (a) Find the tension in thecable. (b) Find the horizontal component of the force exerted on the beam at the wall. (c) Find the vertical component ofthe force...

The horizontal beam in weighs 190 , and its center of gravity is at its center.

= 37.6 from the horizontal ϕ ∘

T

w

= T

w

= F

= 48.8 from the horizontal ϕ ∘

N



Part A

Find the tension in the cable.

Express your answer to three significant figures and include the appropriate units.

ANSWER:

Part B

Find the horizontal component of the force exerted on the beam at the wall.


ANSWER:

Part C

Find the vertical component of the force exerted on the beam at the wall.


ANSWER:

Exercise 11.18Description: A 15000N crane pivots around a frictionfree axle at its base and is supported by a cable making a 25degree(s) angle with the crane (the figure ). The crane is 16 m long and is not uniform, its center of gravity being 7.0 mfrom the axle as...

= 658T

= 527NH

= 95.0NV



A 15000 crane pivots around a frictionfree axle at its base and is supported by a cable making a 25 angle with the crane(the figure ). The crane is 16 long and is not uniform, its center ofgravity being 7.0 from the axle as measured along the crane.The cable is attached 3.0 from the upper end of the crane.

Part A

When the crane is raised to 55 above the horizontal holding an 11000 pallet of bricks by a 2.2 very light cord, findthe tension in the cable.

Express your answer using two significant figures.

ANSWER:

Part B

Find the horizontal component of the force that the axle exerts on the crane.

Enter positive value if the force is rightward and negative value if the force is leftward.

ANSWER:

Part C

Find the vertical component of the force that the axle exerts on the crane.

Enter positive value if the force is upward and negative value if the force is downward.

ANSWER:

Problem 11.44

N ∘

mm

m

∘ N m

= 2.9×104 T N

= 2.5×104 FH N

= 4.1×104 FV N



Description: Sir Lancelot rides slowly out of the castle at Camelot and onto the 12.0mlong drawbridge that passes overthe moat. Unbeknownst to him, his enemies have partially severed the vertical cable holding up the front end of the bridgeso that it will...

Sir Lancelot rides slowly out of the castle at Camelot and onto the 12.0mlong drawbridge that passes over the moat.Unbeknownst to him, his enemies have partially severed the vertical cable holding up the front end of the bridge so that it willbreak under a tension of . The bridge has mass 200 and its center of gravity is at its center. Lancelot, hislance, his armor, and his horse together have a combined mass of 600 .

Part A

Will the cable break before Lancelot reaches the end of the drawbridge?

ANSWER:

Part B

If so, how far from the castle end of the bridge will the center of gravity of the horse plus rider be when the cable breaks?

ANSWER:

Problem 11.50Description: End A of the bar AB in rests on a frictionless horizontal surface, and end B is hinged. A horizontal forceF_vec of magnitude F is exerted on end A. Ignore the weight of the bar. (a) What is the horizontal component of the forceexerted by the bar...

End A of the bar AB in rests on a frictionless horizontal surface, and end B is hinged. A horizontal force of magnitude 290 is exerted on end A. Ignore the weight of the bar.

5.80 × N103 kgkg

yes no

= 9.84 L m

F

N



Part A

What is the horizontal component of the force exerted by the bar on the hinge at B?

Express your answer with the appropriate units.

ANSWER:

Part B

What is the vertical component of the force exerted by the bar on the hinge at B?


ANSWER:

Problem 11.52Description: A loaded cement mixer drives onto an old drawbridge, where it stalls with its center of gravity threequartersof the way across the span. The truck driver radios for help, sets the handbrake, and waits. Meanwhile, a boatapproaches, so the drawbridge ...

A loaded cement mixer drives onto an old drawbridge, where it stalls with its center of gravity threequarters of the way acrossthe span. The truck driver radios for help, sets the handbrake, and waits. Meanwhile, a boat approaches, so the drawbridge israised by means of a cable attached to the end opposite the hinge (the figure ). The drawbridge is 40.0 long and has amass of 18,000 ; its center of gravity is at its midpoint. The cement mixer, with driver, has mass 30,000 . When thedrawbridge has been raised to an angle of 30 above the horizontal, the cable makes an angle of 70 with the surface of thebridge.

= = 290Fh

= = 390

Also accepted: = 387 , = 390

Fv

mkg kg

∘ ∘



Part A

What is the tension in the cable when the drawbridge is held in this position?

ANSWER:

Part B

What is the horizontal component of the force the hinge exerts on the span?

ANSWER:

Part C

What is the vertical component of the force the hinge exerts on the span?

ANSWER:

Problem 11.65Description: A worker wants to turn over a uniform wN rectangular crate by pulling at 53.0 degree(s) on one of itsvertical sides (the figure ). The floor is rough enough to prevent the crate from slipping. (a) What pull is needed to juststart the crate to...

A worker wants to turn over a uniform 1080 rectangular crate by pulling at 53.0 on one of its vertical sides (the figure ).The floor is rough enough to prevent the crate from slipping.

T

= 2.84×105 T N

= 2.18×105 NH N

= 2.88×105 NV N

N ∘



Part A

What pull is needed to just start the crate to tip?

ANSWER:

Part B

How hard does the floor push on the crate?

ANSWER:

Part C

Find the friction force on the crate.

ANSWER:

Part D

What is the minimum coefficient of static friction needed to prevent the crate from slipping on the floor?

ANSWER:

= = 991 P N

= = 1680 N N

= = 792 f N

= 0.472μs



Problem 11.73Description: A gate 4.00 m wide and 2.00 m high weighs w. Its center of gravity is at its center, and it is hinged at A andB. To relieve the strain on the top hinge, a wire CD is connected as shown in . The tension in CD is increased until thehorizontal...

A gate 4.00 wide and 2.00 high weighs 700 . Its center of gravity is at its center, and it is hinged at and . Torelieve the strain on the top hinge, a wire is connected as shown in . The tension in is increased until the horizontalforce at hinge is zero.

Part A

What is the tension in the wire ?


ANSWER:

Part B

What is the magnitude of the horizontal component of the force at hinge ?


ANSWER:

Part C

What is the magnitude of the combined vertical force exerted by hinges and ?


ANSWER:

m m N A BCD CD

A

CD

= = 375T

B

= = 325Fh

A B



Part D

What is the direction of this force?

ANSWER:

= = 512Fv

upward downward

Copyright © 2016 Pearson. All rights reserved.Legal Notice Privacy Policy Permissions

https://media.pearsoncmg.com/shared/legal/

https://media.pearsoncmg.com/shared/privacy/

http://www.pearsoned.com/legal/permissions.htm

Documents

Exercise 11 - Physics and Astronomy at TAMUpeople.physics.tamu.edu/mahapatra/teaching/ch11_mp_sols.pdf · Exercise 11.7 Description: Two ... drawbridge has been raised to an angle