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** Demolition An old building is being demolished by swinging a heavy metal ball from a crane. Suppose that the 100-kg ball swings from a 20-m-long wire at speed 16 m/s as the wire passes the vertical orientation. (a) What tension force must the wire be able to withstand in order not to break? (b) Assume the ball stops after sinking 1.5 m into the wall of the building. What was the average force that the ball exerted on the wall? Indicate any assumptions you made for each part of the problem.
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- Review. A force platform is a tool used to analyze the performance of athletes by measuring the vertical force the athlete exerts on the ground as a function of time. Starting from rest, a 65.0-kg athlete jumps down onto the platform from a height of 0.600 m. While she is in contact with the platform during the time interval 0t 0.800 s, the force she exerts on it is described by the function F = 9 200t 11 500 t2 where F is in newtons and t is in seconds. (a) What impulse did the athlete receive from the platform? (b) With what speed did she reach the platform? (c) With what speed did she leave it? (d) To what height did she jump upon leaving the platform?arrow_forwardThe shower curtain rod in Figure P6.7 is called a tension rod. The rod is not attached to the wall with screws, nails, or glue, but is pressed into the wall instead. Explain why the rod remains at rest, supporting the curtain. Explain why the name is misleading and come up with a better name. FIGURE P6.7arrow_forwardIn a laboratory model of cars skidding to a stop, data are measured for four trials using two blocks. The blocks have identical masses but different coefficients of kinetic friction with a table: k = 0.2 and 0.8. Each block is launched with speed vi = 1 m/s and slides across the level table as the block comes to rest. This process represents the first two trials. For the next two trials, the procedure is repeated but the blocks are launched with speed vi = 2 m/s. Rank the four trials (a) through (d) according to the stopping distance from largest to smallest. If the stopping distance is the same in two cases, give them equal rank. (a) vi = 1 m/s, k = 0.2 (b) vi = 1 m/s, k = 0.8 (c) vi = 2 m/s, k = 0.2 (d) vi = 2 m/s, k = 0.8arrow_forward
- You have a new internship, where you are helping to design a new freight yard for the train station in your city. There will be a number of dead-end sidings where single cars can be stored until they are needed. To keep the cars from running off the tracks at the end of the siding, you have designed a combination of two coiled springs as illustrated in Figure P7.41. When a car moves to the right in the figure and strikes the springs, they exert a force to the left on the car to slow it down. Both springs are described by Hookes law and have spring constants k1 = 1 600 N/m and k2 = 3 400 N/m. After the first spring compresses by a distance of d = 30.0 cm, the second spring acts with the first to increase the force to the left on the car in Figure P7.41. When the spring with spring constant k2 compresses by 50.0 cm, the coils of both springs are pressed together, so that the springs can no longer compress. A typical car on the siding has a mass of 6 000 kg. When you present your design to your supervisor, he asks you for the maximum speed that a car can have and be stopped by your device. Figure P7.41arrow_forwardTo give a pet hamster exercise, some people put the hamster in a ventilated ball andallow it roam around the house(Fig. P13.66). When a hamsteris in such a ball, it can cross atypical room in a few minutes.Estimate the total kinetic energyin the ball-hamster system. FIGURE P13.66 Problems 66 and 67arrow_forwardA 0.500-kg potato is fired at an angle of 80.0 above the horizontal from a PVC pipe used as a “potato gun” and reaches a height of 110.0 m. (a) Neglecting air resistance, calculate the potato’s velocity when it leaves the gun. (b) The gun itself is a tube 0.430 m long. Calculate the average acceleration of the potato in the tube as it goes from zero to the velocity found in (a). (c) What is the average force on the potato in the gun? Express your answer in newtons and as a ratio to the weight of the potato.arrow_forward
- A rectangular block has a length that is five times its width and a height that is three times its width. The blocks surfaces are all identical except for size. When the block is placed on a horizontal tabletop so that the area in contact with the table is length width, it is found that a horizontal force of 10.0 N applied to the block is just sufficient to overcome the static friction force and cause the block to move. The block is then knocked over so that the area in contact with the table is length height. Now, what minimum horizontal force will cause the block to move? Explain.arrow_forwardIn a laboratory model of cars skidding to a stop, data are measured for four trials using two blocks. The blocks have identical masses but different coefficients of kinetic friction with a table: k = 0.2 and 0.8. Each block is launched with speed vi = 1 m/s and slides across the level table as the block comes to rest. This process represents the first two trials. For the next two trials, the procedure is repeated but the blocks are launched with speed vi = 2 m/s. Rank the four trials (a) through (d) according to the stopping distance from largest to smallest. If the stopping distance is the same in two cases, give them equal rank. (a) vi = 1 m/s, = 0.2 (b) vi = 1 m/s, k = 0.8 (c) vi = 2 m/s, = 0.2 (d) vi =2 m/s, k = 0.8arrow_forwardProblems 67. 70. 71. and 72 are grouped. A A block of mass M is placed on a frictionless plane. The plane is inclined at an angle , and the block is a distance d from its end. Of course, we would expect the block to slip down the plane. Suppose we revolve the incline around the vertical axis shown in Figure P6.67 instead. At what period of revolution will the block remain in place on the plane? FIGURE P6.67 Problems 67. 71. and 72.arrow_forward
- A fisherman poles a boat as he searches for his next catch. He pushes parallel to the length of the light pole, exerting a force of 240 N on the bottom of a shallow lake. The pole lies in the vertical plane containing the boats keel. At one moment, the pole makes an angle of 35.0 with the vertical and the water exerts a horizontal drag force of 47.5 N on the boat, opposite to its forward velocity of magnitude 0.857 m/s. The mass of the boat including its cargo and the worker is 370 kg. (a) The water exerts a buoyant force vertically upward on the boat. Find the magnitude of this force. (b) Assume the forces are constant user a short interval of time. Find the velocity of the boat 0.450 s after the moment described, (c) If the angle of the pole with respect to the vertical increased but the exerted force against the bottom remained the same, what would happen to buoyant forte and the acceleration of the boat?arrow_forwardA sled and rider have a total mass of 56.8 kg. They are on a snowy hill. The coefficient of kinetic friction between the sled and the snow is 0.195. The angle of the hills slope measured upward from the horizontal is 19.5. What is the acceleration of the rider? Is the acceleration greater, less than, or equal to your result if a more massive rider uses the same sled on the same hill? Explain.arrow_forward* Question Completion Status: As shown in the figure, a 10-kg block on a perfectly smooth (frictionless) horizontal table is connected by a horizontal string to a 63-kg block that is hanging over the edge of the table. What is the magnitude of the acceleration of the 10-kg block when the other block is gently released? (The gravity acceleration constant g=9.8 m/s) QUESTION 6 10 kg Table 63 kg OA 8.5 m/s2 O B. 7.5 m/s2 OC 9.0 m/s2 O D.8.1 m/s2 ve and Submit to save and submit. Click Save All Answers to save all answers. nere to search 近arrow_forward
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