COLLEGE PHYSICS:VOL.1
2nd Edition
ISBN: 9780134862897
Author: ETKINA
Publisher: PEARSON
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Textbook Question
Chapter 8, Problem 11P
Determine the masses
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The large quadriceps
muscle in the upper leg ter-
Quadriceps
- Tendon
minates at its lower end in a
- Tibia
tendon attached to the upper
end of the tibia (Fig. P8.35a).
The forces on the lower leg
when the leg is extended are
modeled as in Figure P8.35b,
where T is the force of ten-
a
sion in the tendon, w is the
force of gravity acting on
the lower leg, and F is the
force of gravity acting on the
foot. Find T when the ten-
25.0° T
don is at an angle of 25.0°
with the tibia, assuming that
w = 30.0 N, F = 12.5 N, and
the leg is extended at an
angle 0 of 40.0° with the ver-
Figure P8.35
tical. Assume that the center
of gravity of the lower leg is at its center and that the tendon
attaches to the lower leg at a point one-fifth of the way down
the leg.
13
An outdoor chair is suspended from a tree by a single cable of length 1.5 m. The mass of the chair and the person sitting
in it is a total of 85 kg. If someone pulls the chair through a horizontal distance of 80 cm and holds it there:
a. What is the increase in the force exerted by the cable?
b. How much sideways force must be exerted to hold the chair at that location?
A 25.0 kg floodlight in a park is supported at the end of a horizontal beam of negligible mass that is hinged to a pole, as
shown in Figure P8.22. A cable at an angle of 30.0° with the beam helps to support the light.
30,0%
Figure P8.221
(a) Find the tension in the cable.
N
(b) Find the horizontal and vertical forces exerted on the beam by the pole.
horizontal
N (to the right)
vertical
N (upward)
Chapter 8 Solutions
COLLEGE PHYSICS:VOL.1
Ch. 8 - Prob. 1RQCh. 8 - Review Question 8.2 Give an example of a situation...Ch. 8 - Review Question 8.3 You read the following...Ch. 8 - Prob. 4RQCh. 8 - Review Question 8.5 You are trying to hold a heavy...Ch. 8 - Review Question 8.6 Why is a ball hanging by a...Ch. 8 - A falling leaf usually flutters while falling....Ch. 8 - Prob. 2MCQCh. 8 - A hammock is tied with ropes between two trees. A...Ch. 8 - Prob. 4MCQ
Ch. 8 - 5. A physics textbook lies on top of a chemistry...Ch. 8 - What does it mean if the torque of a force is...Ch. 8 - Prob. 7MCQCh. 8 - 8. Why do you tilt your body forward when hiking...Ch. 8 - 9. What does it mean if the torque of a 10-N force...Ch. 8 - What is the maximum angle to the horizontal you...Ch. 8 - Prob. 11MCQCh. 8 - 12. Is it possible for an object not to be in...Ch. 8 - Explain the meaning of torque so that a friend not...Ch. 8 - Prob. 14CQCh. 8 - What are the two conditions of equilibrium? What...Ch. 8 - Give three examples of situations in which an...Ch. 8 - The force that the body muscles exert on bones...Ch. 8 - A ladder leans against a wall. Construct a force...Ch. 8 - Using a crowbar, a person can remove a nail by...Ch. 8 - 20. Is it more difficult to do a sit-up with your...Ch. 8 - Sit on a chair with your feet straight down at the...Ch. 8 - Can you balance the tip of a wooden ruler...Ch. 8 - Try to balance a sharp wooden pencil on your...Ch. 8 - 24. Design a device that you can use to...Ch. 8 - Explain why it is easier to keep your balance...Ch. 8 - A carpenters trick to keep nails from bending when...Ch. 8 - Determine the torques about the axis of rotation P...Ch. 8 - 2. Three 200-N forces are exerted on the beam...Ch. 8 - 3. * A 2.0-m-long, 15-kg ladder is resting against...Ch. 8 - Figure P8.4 shows two different situations where...Ch. 8 - Three friends tie three ropes in a knot and pull...Ch. 8 - Prob. 6PCh. 8 - * Kate joins Jim, Luis, and Adrienne in the...Ch. 8 - You hang a light in front of your house using an...Ch. 8 - * Find the values of the forces the ropes exert on...Ch. 8 - Prob. 10PCh. 8 - Determine the masses m1 and m2 of the two objects...Ch. 8 - * Lifting an engine You work in a machine shop and...Ch. 8 - 13. * More lifting You exert a 630-N force on rope...Ch. 8 - Prob. 14PCh. 8 - 15. * Tightrope walking A tightrope walker wonders...Ch. 8 - 16. * Lifting patients An apparatus to lift...Ch. 8 - 17. A father (80 kg), mother (56 kg), daughter (16...Ch. 8 - Prob. 18PCh. 8 - * You place a 3.0-m-long board symmetrically...Ch. 8 - Prob. 20PCh. 8 - Prob. 21PCh. 8 - Prob. 22PCh. 8 - 23. EST Compare the two different designs of...Ch. 8 - Ray decides to paint the outside of his uncles...Ch. 8 - 25. * A 2.0-m-long uniform beam of mass 8.0 kg...Ch. 8 - * A uniform beam of length / and mass m supports a...Ch. 8 - Prob. 27PCh. 8 - Prob. 28PCh. 8 - Prob. 29PCh. 8 - Prob. 30PCh. 8 - 31. * An 80-kg clown sits on a 20-kg bike on a...Ch. 8 - s center of mass? (Hint: You can think of cutting...Ch. 8 - Leg support A persons broken leg is kept in place...Ch. 8 - Prob. 34PCh. 8 - Prob. 35PCh. 8 - * If the force F shown in Figure P8.35 is 840 N...Ch. 8 - Prob. 37PCh. 8 - 38. * You decide to hang another plant from a...Ch. 8 - Prob. 39PCh. 8 - * What mechanical work must you do to lift a log...Ch. 8 - 41. * A 70-g meter stick has a 30-g piece of...Ch. 8 - * You are trying to tilt a very tall refrigerator...Ch. 8 - Prob. 43PCh. 8 - 44. * You have an Atwood machine (see Figure 4.9 )...Ch. 8 - * EST You stand sideways in a moving train....Ch. 8 - 46. EST Your hand holds a liter of milk (mass...Ch. 8 - EST Body torque You hold a 4.0-kg computer....Ch. 8 - Prob. 48GPCh. 8 - 49. BIO Using triceps to push a table A man pushes...Ch. 8 - Prob. 50GPCh. 8 - Prob. 51GPCh. 8 - Prob. 52GPCh. 8 - 53.* BIO Dumbbell lift IA woman lifts a 3.6-kg...Ch. 8 - s shoulder joint exerts on her humerus.Ch. 8 - Prob. 55GPCh. 8 - * Eiichi has purchased an adjustable hand grip to...Ch. 8 - 57. *BIO While browsing books on neurophysiology,...Ch. 8 - 58. ** Touch detector You have two force sensors...Ch. 8 - * An 80-kg person stands at one end of a 130-kg...Ch. 8 - 61. EST Two people (50 kg and 75 kg) holding hands...Ch. 8 - Prob. 62GPCh. 8 - BIO Muscles work in pairs Skeletal muscles produce...Ch. 8 - BIO Muscles work in pairs Skeletal muscles produce...Ch. 8 - BIO Muscles work in pairs Skeletal muscles produce...Ch. 8 - BIO Muscles work in pairs Skeletal muscles produce...Ch. 8 - BIO Improper lifting and the back A careful study...Ch. 8 - BIO Improper lifting and the back A careful study...Ch. 8 - BIO Improper lifting and the back A careful study...Ch. 8 - BIO Improper lifting and the back A careful study...
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