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The tray dispenser in your cafeteria has broken and is not repairable. The custodian knows that you are good at designing things and asks you to help him build a new dispenser out of spare parts he has on his workbench. The tray dispenser supports a stack of trays on a shelf that is supported by four springs, one at each corner of the shelf. Each tray is rectangular, with dimensions 45.3 cm by 35.6 cm. Each tray is 0.450 cm thick and has a mass of 580 g. The custodian asks you to design a new four-spring dispenser such that when a tray is removed, the dispenser pushes up the remaining stack so that the top tray is at the same position as the just-removed tray was. He has a wide variety of springs that he can use to build the dispenser. Which springs should he use?
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Chapter 7 Solutions
Bundle: Physics for Scientists and Engineers, Volume 2, Loose-leaf Version, 10th + WebAssign Printed Access Card for Serway/Jewett's Physics for Scientists and Engineers, 10th, Multi-Term
- You are participating in a basketball game and as you turn to recieve a ball, a 4 cm long section of your medical collateral ligament stretches to 4.09 cm as a result of a 1150 N tensile force. (100 cm = 1 m; 1 m^2 = 1,000,000 nm^2), (1 m^2 = 1,000,000^2 or 18 mm^2 = 0.000018 m^2). a) how much strain does the ligament withstand? b) how much strain potential energy does the ligament possess in this position if the stiffness value (k) is 9,000 N/m? c) if the ligament has a cross section of 18 mm^2, how much stress does the ligament withstand? Answer parts a-c. Show all work.arrow_forwardReview. Consider the system shown in Figure P10.36 with m1 = 20.0 kg, m2 = 12.5 kg, R = 0.200 m, and the mass of the pulley M = 5.00 kg. Object m2 is resting on the floor, and object m1 is 4.00 m above the floor when it is released from rest. The pulley axis is frictionless. The cord is light, does not stretch, and does not slip on the pulley. (a) Calculate the time interval required for m1 to hit the floor. (b) How would your answer change if the pulley were massless?arrow_forwardWhy is the following situation impossible? A worker in a factory pulls a cabinet across the floor using a rope as shown in Figure P12.36a. The rope make an angle = 37.0 with the floor and is tied h1 = 10.0 cm from the bottom of the cabinet. The uniform rectangular cabinet has height = 100 cm and width w = 60.0 cm, and it weighs 400 N. The cabinet slides with constant speed when a force F = 300 N is applied through the rope. The worker tires of walking backward. He fastens the rope to a point on the cabinet h2 = 65.0 cm off the floor and lays the rope over his shoulder so that he can walk forward and pull as shown in Figure P12.36b. In this way, the rope again makes an angle of = 37.0 with the horizontal and again has a tension of 300 N. Using this technique, the worker is able to slide the cabinet over a long distance on the floor without tiring. Figure P12.36 Problems 36 and 44.arrow_forward
- A scene in a movie has a stuntman falling through a floor onto a bed in the room below. The plan is to have the actor fall on his back, but a researcher has been hired to investigate the safety of this stunt. When the researcher examines the mattress, she sees that it effectively has a spring constant of 77144 N/m77144 N/m for the area likely to be impacted by the stuntman, but it cannot depress more than 13.33 cm13.33 cm without injuring him. To approach this problem, consider a simplified version of the situation. A mass falls through a height of 3.92 m3.92 m before landing on a spring of force constant 77144 N/m.77144 N/m. Calculate the maximum mass that can fall on the mattress without exceeding the maximum compression distance. maximum mass: Based on this crude measurement, is the stunt safe using the proposed mattress? yes no cannot determinearrow_forwardA 1.0 m long board is suspended by two springs from a horizontal ceiling, with one spring at each end of the board. If the board is horizontal, this means that: a. the springs are applying a total force equal to the weight of the board. b. the springs have the same spring constant. c. the board has uniform mass distribution. d. the weight of the board may be considered to be located or applied at the center of the board.arrow_forwardWe analyzed the biceps muscle example with the angle between forearm and upper arm set at 90 degree (see figure below). Find the force exerted by the biceps muscle when the angle is 150 degree and the forearm is in a downward position. (Assume that r_1 = 5.0 cm, r_2 = 12 cm, r_3 = 30 cm, m_a = 2.4kg, and m_b = 4.2 kg. Enter the magnitude.) Narrow_forward
- During a heavy resistance training exercise the valsalva maneuver is used to: Question 27 options: decrease rigidity of the lower torso and increase blood pressure decrease rigidity of the lower torso and decrease blood pressure increase rigidity of the lower torso and decrease blood pressure increase rigidity of the lower torsal and increase blood pressure Question 28 Which of the following is the definition of power? Question 28 options: mass X acceleration force X distance force X velocity tourque X timearrow_forwardA bar weighing 26.0 N is supported horizontally on each end by two hangingsprings, each 15.0 cm long, with spring constants 0.970 N/cm and 1.45 N/cm,respectively. The bar is 6.00 m long and has a center of mass 2.00 m from thespring with constant 0.970 N/cm. How far does each spring stretch?arrow_forwardA spring with a constant of 300 N/m is stretched 1.5 m. What is the force in the spring? 100 N 50 N 300 N 150 N 450 N 200 Narrow_forward
- A tow truck is pulling a car out of a ditch by means of a steel cable that is 9.2 m long and has a radius of 0.50 cm. When the car just begins to move, the tension in the cable is 279.6 N. How much has the cable stretched from its initial length? Assume Ysteel is 2x1011 N/m2arrow_forwardA 2.35-kg uniform bar oflength l = 1.30 m is heldin a horizontal position bythree vertical springs as inFigure P8.83. The two lowersprings are compressed andexert upward forces on thebar of magnitude F1= 6.80 Nand F2 = 9.50 N, respectively.Find (a) the force Fs exertedby the top spring on the bar,and (b) the location x of the upper spring that will keep thebar in equilibrium.arrow_forwardThe force required to compress a non-standard spring as a function of displacement from equilibrium x is given by the equation F(x) = ax2 - bx, where a = 55 N/m2, b = 8 N/m, and the positive x direction is in the compression direction of the spring.arrow_forward
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