COLLEGE PHYSICS
2nd Edition
ISBN: 9781711470832
Author: OpenStax
Publisher: XANEDU
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Chapter 9, Problem 29PE
To determine
The force exerted by the upper leg muscle to lift the mass at a constant speed.
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ASK YOUR TEACHER PRACTICE ANOTHER
The chewing muscle, the masseter, is one of the strongest in the human body. It is attached to the mandible (lower jawbone) as shown in figure (a). The jawbone is pivoted about a
socket just in front of the auditory canal. The forces acting on the jawbone are equivalent to those acting on the curved bar in figure (b).
DETAILS SERCP11 8.3.P.033.
Mandible
magnitude of R
magnitude of
Masseter
Need Help?
-7.50 cm -
3.50 cm
is the force exerted by the food being chewed against the jawbone, is the force of tension in the masseter, and is the force everted by the socket on the mandible. Find and i
(in N) for a person who bites down on a piece of steak with a force of 53.5 N
MY NOTES
A 50 N hand and forearm are held at a 35° angle to the vertically oriented humerus. The CG of the forearm and hand is located at a distance of 12.5 cm from the joint center at the elbow, and the elbow flexor muscles attach at an average distance of 2.5 cm from the joint center. (Assume that the muscles attach at an angle of 35° to the forearm bones.)
How much force must the forearm flexors exert if a 50 N weight is held in the hand at a distance along the arm of 25 cm?
1. The figure below shows the normal configuration of the head with proper posture. The center of
mass for the weight of the skull is labeled W and the muscles that attach to the back of the skull are
labeled M.
Assume all quantities are correct to 2 significant figures.
M
W
a) Determine the mechanical advantage of the skull muscles when d₁ 20 mm and d₂ = 26 mm.
Hint: Which force on the fulcrum (rotation point) is the effort, and which is the load?
Enter to 2 significant figures
Mechanical Advantage:
b) Improper posture and positioning of the head can lead to muscle tension headaches. If the head
begins to shift forward while studying or reading, the center of mass moves further from the fulcrum
or pivot point. It is a subtle change, but the figure below shows the head shifted forward. The center
of mass for the weight of the skull is labeled W and the muscles that attach to the back of the skull
are labeled M. Determine the new mechanical advantage of the skull muscles when d₁ = 16 mm…
Chapter 9 Solutions
COLLEGE PHYSICS
Ch. 9 - What can you say about the velocity of a moving...Ch. 9 - Under what conditions can a rotating body be in...Ch. 9 - What three factors affect the torque created by a...Ch. 9 - A wrecking ball is being used to knock down a...Ch. 9 - Mechanics put a length of Pipe over the handle of...Ch. 9 - Prob. 6CQCh. 9 - Explain the need for tall towers on a suspension...Ch. 9 - When visiting some countries, you may see a person...Ch. 9 - Prob. 9CQCh. 9 - Prob. 10CQ
Ch. 9 - Why are the forces exerted on the outside world by...Ch. 9 - Explain why the forces in our joints are several...Ch. 9 - Why are the forces exerted on the outside world by...Ch. 9 - Explain why the forces in our joints are several...Ch. 9 - Certain of dinosaurs were bipedal (walked on two...Ch. 9 - Swimmers and athletes during competition need to...Ch. 9 - If the maximum force the biceps muscle can exert...Ch. 9 - Suppose the biceps muscle was attached through...Ch. 9 - Explain one of the reasons why pregnant women...Ch. 9 - (a) When opening a door, you push on it...Ch. 9 - When tightening a bolt, you push perpendicularly...Ch. 9 - Two children push on opposite sides of a door...Ch. 9 - Use the second condition for equilibrium (net =0 )...Ch. 9 - Repeat the seesaw problem in Example 9.1 with the...Ch. 9 - Prob. 6PECh. 9 - Two children of mass 20.0 kg and 30.0 kg sit...Ch. 9 - Prob. 8PECh. 9 - A person carries a plank of wood 2.00 m long with...Ch. 9 - Prob. 10PECh. 9 - Prob. 11PECh. 9 - Prob. 12PECh. 9 - Prob. 13PECh. 9 - Prob. 14PECh. 9 - Prob. 15PECh. 9 - Prob. 16PECh. 9 - To get up on the roof, a person (mass 70.0 kg)...Ch. 9 - Prob. 18PECh. 9 - Prob. 19PECh. 9 - Suppose you needed to raise a 250-kg mower a...Ch. 9 - Prob. 21PECh. 9 - Prob. 22PECh. 9 - Prob. 23PECh. 9 - Prob. 24PECh. 9 - Prob. 25PECh. 9 - Prob. 26PECh. 9 - Prob. 27PECh. 9 - Prob. 28PECh. 9 - Prob. 29PECh. 9 - Prob. 30PECh. 9 - Prob. 31PECh. 9 - Prob. 32PECh. 9 - Prob. 33PECh. 9 - Prob. 34PECh. 9 - Prob. 35PECh. 9 - Integrated Concepts Suppose we replace the 4.0-kg...Ch. 9 - Prob. 37PECh. 9 - You have just planted a sturdy 2-m-tall palm tree...Ch. 9 - Unreasonable Results Suppose two children are...Ch. 9 - Construct Your Own Problem Consider a method for...Ch. 9 - Prob. 1TPCh. 9 - Prob. 2TPCh. 9 - Prob. 3TPCh. 9 - Prob. 4TPCh. 9 - Prob. 5TPCh. 9 - Prob. 6TPCh. 9 - Prob. 7TPCh. 9 - Prob. 8TPCh. 9 - Prob. 9TPCh. 9 - Prob. 10TPCh. 9 - Prob. 11TP
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- 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? _______ Warrow_forwardA 50 N hand and forearm are held at a 35° angle to the vertically oriented humerus. The CG of the forearm and hand is located at a distance of 12.5 cm from the joint center at the elbow, and the elbow flexor muscles attach at an average distance of 2.5 cm from the joint center. (Assume that the muscles attach at an angle of 35° to the forearm bones.) How much force must be exerted by the forearm flexors to maintain this position?arrow_forwardThe figure below shows an outstretched arm (0.61 m in length) that is parallel to the floor. The arm is pulling downward against the ring attached to the pulley system, in order to hold the 98 N weight stationary. To pull the arm downward, the latissimus dorsi muscle applies the force M in the figure, at a point that is 0.069 m from the should joint and oriented at an angle of 29°. The arm has a weight of 47 N and a center of gravity (cg) that is located 0.28 m from the shoulder joint. 0.61 m 0.28 m 0.069 m Axis at 98 N shoulder joint cg 29 Aldentify all the forces on the arm and draw an accurate and complete free body diagram on both the arm and the 98 N weight. You may draw on the figure if you wish. B Write down the correct equation of motion ON THE 98 N WEIGHT by summing all the forces acting on it using Newton's 2nd Law of Motion. You must identify and draw your chosen coordinate system. ( Write down the correct equation of motion ON THE ARM by summing all the forces acting on it…arrow_forward
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