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Over the Christmas break, you are making some extra money for buying presents by working in a factory, helping to move crates around. At one particular time, you find that all the handtrucks, dollies, and carts are in use, so you must move a crate across the room a straight-line distance of 35.0 m without the assistance of these devices. You notice that the crate has a rope attached to the middle of one of its vertical faces. You decide to move the crate by pulling on the rope. The crate has a mass of 130 kg, and the coefficient of kinetic friction between the crate and the concrete floor is 0.350. (a) Determine the angle relative to the horizontal at which you should pull upward on the rope so that you can move the crate over the desired distance with the force of the smallest magnitude. (b) At this angle of pulling on the rope, how much work do you do in dragging the crate over the desired distanced?
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Chapter 7 Solutions
Physics for Scientists and Engineers with Modern Physics
- A small block slides down a frictionless track whose shape is described by y = (x^2) /d for x<0 and by y = -(x^2)/d for x>0.The value of d is d = 4.72 m. The block starts at x = 0, and is given a push to the left with an initial speed of 5.37 m/s, so it starts sliding up the track to the left. At what value of x will the block reverse direction and start sliding back down? -1.47 m -2.63 m 2.63 m 1.47 marrow_forwardA small block slides down a frictionless track whose shape is described by y = (x^2) /d for x<0 and by y = -(x^2)/d for x>0. D = 2.37 m. The block starts at x = 0, and is given a push to the left with an initial speed of 2.76 m/s, so it starts sliding up the track to the left. At what value of x will the block reverse direction and start sliding back down? 0.39 m -0.39 m -0.96 m 0.96 marrow_forwardA boy shoves his stuffed toy zebra down a frictionless chute. It starts at a height of 1.11 m1.11 m above the bottom of the chute with an initial speed of 1.53 m/s1.53 m/s. The toy animal emerges horizontally from the bottom of the chute and continues sliding along a horizontal surface with a coefficient of kinetic friction of 0.2850.285. How far from the bottom of the chute does the toy zebra come to rest? Assume ?=9.81 m/s2g=9.81 m/s2.arrow_forward
- A leashed chihuahua is held by its owner in a park. The dog is walking and undergoes a displacementi = (0. 5 m)î + (1.8 m)j. If the tension in the leash is T = (-10.0î + 7.8ĵ)N. What is the angle between the two vectors?arrow_forwardA 10 kg box is being pushed across a rough surface with a constant speed of 2 m/s. The person pushing the box slips and stops pushing. The box continues to slide across the surface before coming to rest. If the coefficient of friction between the crate and the surface is 0.1, how far does the box travel before coming to rest?arrow_forwardThe figure shows a 2400 kg cable car descending a high hill. A counterweight of mass 2200 kg on the other side of the hill aids the brakes in controlling the cable car's speed. The rolling friction of both the cable car and the counterweight are negligible. How much braking force does the cable car need to descend at constant speed? Counterweight 200 m 30° 20° 2200 N 3300 N 980 N 4400 Narrow_forward
- An airplane of mass 3.60 × 105 kg experienced a problem with all its tires when it was about to touch down at a runway of an airport. The tires were deadlocked and not able to roll. The airplane began to skid once it touched down and left behind a 728 m long skid mark on the runway before it came to a stop. Even though everyone on the airplane was safe, the pilot was accused of failing to land the airplane within the allowable speed limit of 80.0 m/s and his pilot license was suspended. Given that the coefficient of kinetic friction between the tires and runway was 0.496. (i) Determine the work done by friction on the tires.(ii) Use the Work-Energy Theorem to evaluate if the suspension of the pilot’s license should be revoked. #This is an exercise question, please help. Thank You.arrow_forwardIn (Figure 1), F={300i-100j+550k}NF= (300i-100j+550k)N. Determine the magnitude of the projection of the force FF acting along the cable BA◆◆. Express your answer to three significant figures and include the appropriate units. Figure 2m 6m 1 of 1 3marrow_forwardThe 2013 women’s pole vault World Record of 4.89 m belongs to Yelena Isinbayeva of Russia. If the pole vault mat has the dimensions of 6.0 m×8.0 m×0.8 m , what is the vertical speed of the vaulter right before she strikes the mat?arrow_forward
- Carol wants to move her 32kg sofa to a different room in the house. She places "sofa disks", slippery disks with mu k =.080 , on the carpet, under the feet of the sofa. She then pushes the sofa at a steady.4 .4 m/s across the floor. How much force does she apply to the sofa?arrow_forwardA ball with a unknown mass is attached to a cable and suspended from the ceiling. The distance from the ceiling to the hanging is 1.9 m (the length of the cable). A person pulls the ball so the cable makes an angle of 64 degrees to the vertical. Determine the maximum speed that can be reached by the mass (in m/s).arrow_forwardThe 2090 kg cable car shown in the figure descends a 200-m-high hill. In addition to its brakes, the cable car controls its speed by pulling an 1860 kgcounterweight up the other side of the hill. The rolling friction of both the cable car and the counterweight are negligible. How much braking force does the cable car need to descend at constant speed? One day the brakes fail just as the cable car leaves the top on its downward journey. What is the runaway car's speed at the bottom of the hill?arrow_forward
- Glencoe Physics: Principles and Problems, Student...PhysicsISBN:9780078807213Author:Paul W. ZitzewitzPublisher:Glencoe/McGraw-Hill