College Physics
2nd Edition
ISBN: 9780134601823
Author: ETKINA, Eugenia, Planinšič, G. (gorazd), Van Heuvelen, Alan
Publisher: Pearson,
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Textbook Question
Chapter 8, Problem 53GP
* BIO Dumbbell lift IA woman lifts a 3.6-kg dumbbell in each hand with her arm in a horizontal position at the side of her body and holds it there for 3 s (see Figure P8.53) What force does the deltoid muscle in her shoulder exert on the humerus bone while holding the dumbbell? The deltoid attaches 13 cm from the shoulder joint and makes a
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Students have asked these similar questions
A. Explain why placing your hands behind your head rather than placing them on your stomach makes sit-ups more difficult.
B. Explain why it is easier (it requires a smaller force) to open a large jar than a small one.
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
Consider the following figure.
a.
What force in newtons should the woman in the figure exert on the floor with each hand to do a push-up? Assume that she moves up at a constant speed.
_______ N
b.
The triceps muscle at the back of her upper arm has an effective lever arm of 1.76 cm, and she exerts force on the floor at a horizontal distance of 18.0 cm from the elbow joint. Calculate the magnitude of the force in newtons in each triceps muscle.
_________ N
Compare the magnitude of the total force exerted by both triceps muscles to her weight.
total force exerted by both triceps muscles/her weight =
c. How much work does she do in joules if her center of mass rises 0.255 m?
_______ J
d.
What is her useful power output in watts if she does 21 push-ups in one minute?
_______ W
Chapter 8 Solutions
College Physics
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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Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, physics and related others by exploring similar questions and additional content below.Similar questions
- (a) What force should the woman in Figure 9.45 exert on the floor with each hand to do a push-up? Assume that she moves up at a constant speed. (b) The triceps muscle at the back of her upper arm has an effective lever arm of 1.75 cm, and she exerts force on the floor at a horizontal distance of 20.0 cm from the elbow joint. Calculate the magnitude of the force in each triceps muscle, and compare it to her weight. (c) How much work does she do if her center of mass rises 0.240 m? (d) What is her useful power output if she does 25 pushups in one minute?arrow_forwardTorque and the Two Conditions for Equilibrium 17. The arm in Figure P8.17 weighs 41.5 N. The force of gravity acting on the arm acts through point A. Determine the magnitudes of the tension force Ft, in the deltoid muscle and the force Fs exerted by the shoulder on the humerus (upper-arm bone) to hold the arm in the position shown. Figure P8.17arrow_forwardMany of the elements in horizontal-bar exercises can be modeled by representing the gymnast by four segments consisting of arms, torso (including the head), thighs, and lower legs, as shown in Figure P8.15a. Inertial parameters for a particular gymnast are as follows: Note that in Figure P8.l5a rcg is the distance to the center of gravity measured from the joint closest to the bar and the masses for the arms, thighs, and legs include both appendages. I is the moment of inertia of each segment about its center of gravity. Determine the distance from the bar to the center of gravity of the gymnast for the two positions shown in Figures P8.15b and P8.15c. Figure P8.15arrow_forward
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- If you hold your arm outstretched with palm upward, as shown, the force to keep your arm from falling comes from your deltoid muscle. The arm of a typical person has mass 4.0 kg and the distances and angles shown in the figure.a. What force must the deltoid muscle provide to keep the arm in this position?b. By what factor does this force exceed the weight of the arm?arrow_forwardQ2) Machine Curls and the Biceps Muscle. A woman performs seated machine curls to strengthen her biceps muscles (the figure below). She uses a weight of 10 kg. Horizontal distance between her elbows (A) and the bottom of the frictionless pulley (B) is 60 cm. Vertical distance between the same points is 20 cm. Determine the force exerted by the holding bar on the woman's hands when her arm is at 45° with the horizontal. At that moment, the weight has an upward acceleration of 3 m/s2. DB DIA 32cm 20cm PAB 45 60cmarrow_forwardView Policies Current Attempt in Progress Concept Simulation 9.1 illustrates how the forces can vary in problems of this type. A hiker, who weighs 668 N, is strolling through the woods and crosses a small horizontal bridge. The bridge is uniform, weighs 4590 N, and rests on two concrete supports, one on each end. He stops 1/6 of the way along the bridge. What is the magnitude of the force that a concrete support exerts on the bridge (a) at the near end and (b) at the far end? (a) Number i Units (b) Number Unitsarrow_forward
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What is Torque? | Physics | Extraclass.com; Author: Extraclass Official;https://www.youtube.com/watch?v=zXxrAJld9mo;License: Standard YouTube License, CC-BY