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Review. Why is the following situation impossible? An athlete tests her hand strength by having an assistant hang weights from her belt as she hangs onto a horizontal bar with her hands. When the weights hanging on her belt have increased to 80% of her body weight, her hands can no longer support her and she drops to the floor. Frustrated at not meeting her hand-strength goal, she decides to swing on a trapeze. The trapeze consists of a bar suspended by two parallel ropes, each of length ℓ, allowing performers to swing in a vertical circular are (Fig. P8.38). The athlete holds the bar and steps off an elevated platform, starting from rest with the ropes at an angle θi = 60.0° with respect to the vertical. As she swings several times back and forth in a circular are, she forgets her frustration related to the hand-strength test. Assume the size of the performer’s body is small compared to the length ℓ and air resistance is negligible.
Figure P8.38
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- An online video daredevil is filming a scene where he swings across a river on a vine. The safety crew must use a vine with enough strength so that it doesn't break while swinging. The daredevil's mass is 86.0 kg, the vine is 11.0 m long, and the speed of the daredevil at the bottom of the swing has been determined to be 7.00 m/s. What is the minimum tension force (in N) the vine must be able to support without breaking?arrow_forwardAn online video daredevil is filming a scene where he swings across a river on a vine. The safety crew must use a vine with enough strength so that it doesn't break while swinging. The daredevil's mass is 86.0 kg, the vine is 11.0 m long, and the speed of the daredevil at the bottom of the swing has been determined to be 8.40 m/s. What is the minimum tension force (in N) the vine must be able to support without breaking? Narrow_forwardYou are working with a team that is designing a new roller coaster-type amusement park ride for a major theme park. You are present for the testing of the ride, in which an empty 190 kg car is sent along the entire ride. Near the end of the ride, the car is at near rest at the top of a 102 m tall track. It then enters a final section, rolling down an undulating hill to ground level. The total length of track for this final section from the top to the ground is 250 m. For the first 230 m, a constant friction force of 400 N acts from computer-controlled brakes. For the last 20 m, which is horizontal at ground level, the computer increases the friction force to a value required for the speed to be reduced to zero just as the car arrives at the point on the track at which the passengers exit. (a) Determine the required constant friction force (in N) for the last 20 m for the empty test car. 4905.89 N (b) Find the highest speed (in m/s) reached by the car during the final section of track…arrow_forward
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- A man pushing a crate of mass m = 92.0 kg at a speed of v = 0.875 m/s encounters a rough horizontal surface of length ℓ = 0.65 m as in the figure below. If the coefficient of kinetic friction between the crate and rough surface is 0.355 and he exerts a constant horizontal force of 296 N on the crate. A man pushes a crate labeled m, which moves with a velocity vector v to the right, on a horizontal surface. The horizontal surface is textured from the right edge of the crate to a horizontal distance ℓ from the right edge of the crate. (a) Find the magnitude and direction of the net force on the crate while it is on the rough surface. magnitude N direction ---Select--- opposite as the motion of the crate same as the motion of the crate (b) Find the net work done on the crate while it is on the rough surface. J(c) Find the speed of the crate when it reaches the end of the rough surface. m/sarrow_forwardYou are an industrial engineer with a shipping company. As part of the package-handling system, a small box with mass 1.20 kg is placed against a light spring that is compressed 0.280 m. The spring, whose other end is attached to a wall, has force constant k = 48.0 N/m. The spring and box are released from rest, and the box travels along a horizontal surface for which the coefficient of kinetic friction with the box is μ = 0.300. When the box has traveled 0.280 m and the spring has reached its equilibrium length, the box loses contact with the spring. Part A What is the speed of the box at the instant when it leaves the spring? Express your answer with the appropriate units. V = Submit Value Part B X Incorrect; Try Again Umax = Previous Answers Request Answer Units What is the maximum speed of the box during its motion? Express your answer with the appropriate units. Value ? Units ?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_forward
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