Concept explainers
When you bend your knee, the quadriceps muscle is stretched. This increases the tension in the quadriceps tendon attached to your kneecap (patella), which, in turn, increases the tension in the patella tendon that attaches your kneecap to your lower leg bone (tibia). Simultaneously, the end of your upper leg bone (femur) pushes outward on the patella. Figure P5.5 shows how these parts of a knee joint are arranged. What size force does the femur exert on the kneecap if the tendons are oriented as in the figure and the tension in each tendon is 60 N?
Figure P5.5
Learn your wayIncludes step-by-step video
Chapter 5 Solutions
MASTERING PHYS T/A COLLEGE PHYSICS >I<
Additional Science Textbook Solutions
University Physics with Modern Physics (14th Edition)
College Physics (10th Edition)
Essential University Physics (3rd Edition)
Physics: Principles with Applications
Physics for Scientists and Engineers with Modern Physics
Applied Physics (11th Edition)
- A skier starts at rest at the top of a large hemispherical hill (Fig. P7.63). Neglecting friction, show that the skier will leave the hill and become airborne at a distance h = R/3 below the top of the hill. Hint: At this point, the normal force goes to zero. Figure P7.63arrow_forwardA car is stuck in the mud. A tow truck pulls on the car with the arrangement shown in Figure P5.24. The tow cable is under a tension of 2 500 N and pulls downward and to the left on the pin at its upper end. The light pin is held in equilibrium by forces exerted by the two bars A and B. Each bar is a strut; that is, each is a bar whose weight is small compared to the forces it exerts and which exerts forces only through hinge pins at its ends. Each strut exerts a force directed parallel to its length. Determine the force of tension or compression in each strut. Proceed as follows. Make a guess as to which way (pushing or pulling) each force acts on the top pin. Draw a free-body diagram of the pin. Use the condition for equilibrium of the pin to translate the free-body diagram into equations. From the equations calculate the forces exerted by struts A and B. If you obtain a positive answer, you correctly guessed the direction of the force. A negative answer means that the direction should be reversed, but the absolute value correctly gives the magnitude of the force. If a strut pulls on a pin. it is in tension. If it pushes, the strut is in compression. Identify whether each strut is in tension or in compression.arrow_forwardAll object of mass m = 500 kg is suspended from the ceiling of an accelerating truck as shown in Figure P6.21. Taking a = 3.00 m/s2, find (a) the angle 0 that the string makes with the vertical and (b) the tension T in the string.arrow_forward
- Consider the three connected objects shown in Figure P5.43. Assume first that the inclined plane is frictionless and that the system is in equilibrium. In terms of m, g, and , find (a) the mass M and (b) the tensions T1 and T2. Now assume that the value of M is double the value found in part (a). Find (c) the acceleration of each object and (d) the tensions T1 and T2. Next, assume that the coefficient of static friction between m and 2m and the inclined plane is s and that the system is in equilibrium. Find (e) the maximum value of M and (f) the minimum value of M. (g) Compare the values of T2 when M has its minimum and maximum values. Figure P5.43arrow_forwardA certain orthodontist uses a wire brace to align a patients crooked tooth as in Figure P5.1. The tension in the wire is adjusted to have a magnitude of 18.0 N. Find the magnitude of the net force exerted by the wire on the crooked tooth. Figure P5.1arrow_forwardThe person in Figure P5.6 weighs 170 lb. As seen from the front, each light crutch makes an angle of 22.0 with the vertical. Half of the persons weight is supported by the crutches. The other half is supported by the vertical forces of the ground on the persons feet. Assuming that the person is moving with constant velocity and the force exerted by the ground on the crutches acts along the crutches, determine (a) the smallest possible coefficient of friction between crutches and ground and (b) the magnitude of the compression force in each crutch. Figure P5.6arrow_forward
- As shown in Figure CQ5.22, student A, a 55-kg girl, sits on one chair with metal runners, at rest on a classroom floor. Student B, an 80-kg boy, sits on an identical chair. Both students keep their feet off the floor. A rope runs from student As hands around a light pulley and then over her shoulder to the hands of a teacher standing on the floor behind her. The low-friction axle of the pulley is attached to a second rope held by student B. All ropes run parallel to the chair runners. (a) If student A pulls on her end of the rope, will her chair or will Bs chair slide on the floor? Explain why. (b) If instead the teacher pulls on his rope end, which chair slides? Why this one? (c) If student B pulls on his rope, which chair slides? Why? (d) Now the teacher ties his end of the rope to student As chair. Student A pulls on the end of the rope in her hands. Which chair slides and why? Figure CQ5.22arrow_forward(a) Find the tension in each cable supporting the 6.00 102-N cat burglar in Figure P4.35. (b) Suppose the horizontal cable were reattached higher up on the wall. Would the tension in the other cables increase, decrease, or stay the same? Why? Figure P4.35arrow_forwardq11 A runner, Ricky ASHER, is travelling at 8.47 m/s. Turning into the final straight, they accelerate at a constant 1.0 m/s2. Their mass is 71 kg. Neglecting air resistance, what vertical force (in kN) does the track exert on them? Enter the numerical part of your answer, rounded to two significant figures.arrow_forward
- You are pushing a box, apply Fa = 90 N. The box's mass is 25 kg. The coefficients of friction are μs =0.60 and μk = 0.4. The box was stationary when you began pushing. Calculate the frictional force magnitude exerted on the box by the floor b) In the previous problem, what is the minimum force that you must apply (Fa) to start the box accelerating? (The computer-generated numbers are now M = 22 kg, μs =0.57, and μk = 0.47.)arrow_forwardAn animal with a mass of 25 kg starts to slide while standing on the top of a 10 m high pole as shown in the figure, and its speed becomes 4 m / s when it reaches the bottom of the pole. What is the friction force applied by the pole affecting the animal? (g = 10 m / s ^ 2)arrow_forwardA child on a sled starts from rest at the top of a 15° slope. If the trip to the bottom takes 15.2 s how long is the slope? Assume that frictional forces may be neglected. A) 147 m B) 293 m C) 1130 m D) 586 marrow_forward
- Principles of Physics: A Calculus-Based TextPhysicsISBN:9781133104261Author:Raymond A. Serway, John W. JewettPublisher:Cengage LearningPhysics for Scientists and Engineers, Technology ...PhysicsISBN:9781305116399Author:Raymond A. Serway, John W. JewettPublisher:Cengage LearningPhysics for Scientists and Engineers with Modern ...PhysicsISBN:9781337553292Author:Raymond A. Serway, John W. JewettPublisher:Cengage Learning
- Physics for Scientists and EngineersPhysicsISBN:9781337553278Author:Raymond A. Serway, John W. JewettPublisher:Cengage LearningCollege PhysicsPhysicsISBN:9781285737027Author:Raymond A. Serway, Chris VuillePublisher:Cengage LearningCollege PhysicsPhysicsISBN:9781305952300Author:Raymond A. Serway, Chris VuillePublisher:Cengage Learning