Concept explainers
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?
Trending nowThis is a popular solution!
Chapter 7 Solutions
PHYSICS FOR SCI.AND ENGR W/WEBASSIGN
- Embassy Motorcycles (EM) manufactures two lightweight motorcycles designed for easy handling and safety. The EZ-Rider model has a new engine and a low profile that make it easy to balance. The Lady-Sport model is slightly larger, uses a more traditional engine, and is specifically designed to appeal to women riders. Embassy produces the engines for both models at its Des Moines, Iowa, plant. Each EZ-Rider engine requires 6 hours of manufacturing time and each Lady-Sport engine requires 3 hours of manufacturing time. The Des Moines plant has 2100 hours of engine manufacturing time available for the next production period. Embassy’s motorcycle frame supplier can supply as many EZ-Rider frames as needed. However, the Lady-Sport frame is more complex and the supplier can only provide up to 280 Lady-Sport frames for the next production period. Final assembly and testing requires 2 hours for each EZ-Rider model and 2.5 hours for each Lady-Sport model. A maximum of 1000 hours of assembly and…arrow_forwardThe structure shown below is supported by a pin and roller on an inclined surface that is parallel to the line connecting joints A and G. Given that P = 490 lb. NOTE: This is a multi-part question. Once an answer is submitted, you will be unable to return to this part. 18 in.18 in.18 in.18 in.→ P| P❘ P P P E D C B 12 in. F 12 in. + H G Determine the force supported by the members CD, CI, and J. Enter forces as positive numbers if the member is in tension and as negative numbers if the member is in compression. (Round the final answers to four decimal places. Include a minus sign if necessary.) The force supported by the members CD, Cl, and IJ is as follows: FCD= FCI= lb FIJ= lb lbarrow_forwardThe drawing shows two crates that are connected by a steel wire that passes over a pulley. The unstretched length of the wire is 1.5 m, and its cross-sectional area is 1,3×10-5 m2. The pulley is frictionless and massless. When the crates are accelerating, determine the change in length of the wire. Ignore the mass of the wire.arrow_forward
- Group Problem: You are planning to build a log cabin in Northern Minnesota on a remote hill with a beautiful view of the setting sun. You will drag the logs up a long sometimes rocky hill to the building site by means of a rope attached to a winch. You will need a rope for this job so you aim to know how much weight the rope would safely support. You are operating on a tight budget so matching the rope strength would be a cost saver. You know that the logs are heavy, and estimate the heaviest as 1,000 lbs. From maps you verify the hill is steeped at an angle of 8 = 70° with respect to the vertical, and you estimate a coefficient of kinetic friction between a log and the earthen hill as 0.5. When pulling a log you will ensure that the uphill acceleration is never more than 3.0 ft/s². The maximum recommended load is th of the nominal strength for the ropes considered as stated on the product labels, you have three ropes in mind: 12 kN, 18 kN, & 24 kN. Which one of these three rope…arrow_forwardWhen using a ladder, it is important to place it against a wall at a safe angle. A ladder could tip over backwards if the angle is too large or the ladder could slide down the wall if the angle is too small. For a ladder to be placed at a safe angle, the ratio of the working length (how far you climb the ladder) to how far the ladder is from the wall should be 4 : 1. What angle should we place place our ladders at so that they are safe when we use them?arrow_forwardA board sits in equilibrium. On the left end, there is a wire that supports the board from the ceiling, and to the right, there is a sawhorse that supports the board from the ground. The sawhorse is a distance d= 1/5l from the right edge of the board. There is a block with mass ms= 4.5kg that is a distance 3/4l from the right edge of the board. Finally the board has a mass mb= 11kg. e) What is the force of tension and normal force on the board?arrow_forward
- A board sits in equilibrium. On the left end, there is a wire that supports the board from the ceiling, and to the right, there is a sawhorse that supports the board from the ground. The sawhorse is a distance d= 1/5l from the right edge of the board. There is a block with mass ms= 4.5kg that is a distance 3/4l from the right edge of the board. Finally the board has a mass mb= 11kg. e) What is the force of tension and normal force on the board?arrow_forwardYour answer is partially correct. African elephants are the largest land animals. They consume approximately 10% of their body weight in food each day, which for an adult male, can be 1000 lb. of vegetation! Their diet consists mostly of grasses, bamboo, tree bark, and fruit. They also like to dine on tree leaves. To reach them, they often stand up on their hind legs and extend their trunks (see the figure). The elephant in the figure is in equilibrium. The location of the elephant's center of mass is shown, and the axis of rotation has been chosen to correspond to the hip joint. The forces in the elephant's free-body diagram are shown, and there is a static friction force between the elephant's back feet and the ground. Use the following information and calculate the magnitude of the tension in the elephant's trunk T (m = 4540 kg, FN = 'fs=133 cm, rcg = 76.0 cm, r = 229 cm). Number 1103.035 +x Axis of rotation Units N 165⁰ 60⁰ W =FN 30° FN 10° Michael Poliza/Caters News Agencyarrow_forwardA person opens a door by applying a 13-N force perpendicular to it at a distance 0.90 m from the hinges. The door is pushed wide open (to 120 ° ) in 2.6 s How much work was done? Express your answer using two significant figures. να ΑΣφ J Submit Request Answer Part B What was the average power delivered? Express your answer using two significant figures. Hνα ΑΣφarrow_forward
- A medical technician uses a pair of 0.125m long tweezers to remove a wood sliver from a patient. The technician is applying 5 N of squeezing force to the tweezers. If more than 1/5 lb of force is applied to the sliver, it will break and become difficult to remove. Assume the squeezing force is applied at 90 degrees to the tweezers. What is the mechanical advantage?arrow_forwardA uniform 10.0 m beam of mass 300 kg extends over a ledge, as in Figure. The beam is not attached but simply rests on the surface. A 60.0 kg student intends to position the beam so that he can walk to the end of it. What is the maximum distance the beam can extend past the end of the ledge and still allow him to perform this feat?arrow_forwardA ladder of negligible mass composed of two L-long rails that are hinged at the top, is placed on top of a frictionless floor. A metal bar, connecting both rails halfway up the ladder is placed so that the two rails make an angle of 0 = 43.0 at the apex. Lastly, a M = 4.30 [kg] block is placed 2/3 of the way up the ladder, as shown. 213 L Ө L H # A) what is the magnitude of the tension in the metal bar? B) What is the magnitude of the normal force exerted on the bottom right side of the ladder? C) What is the magnitude of the normal force exerted on the bottom left side of the ladder? D) What is the magnitude of the force the right side of the ladder exerts on its left side?arrow_forward
- College PhysicsPhysicsISBN:9781938168000Author:Paul Peter Urone, Roger HinrichsPublisher:OpenStax College