Concept explainers
* BIO Bone break The tibia bone in the lower leg of an adult human will break if the compressive force on it exceeds about
N (we assume that the ankle is pushing up). Suppose that a student of mass 60 kg steps off a chair that is 0.40 m above the floor. If landing stiff-legged on the surface below, what minimum stopping distance does he need to avoid breaking his tibias? Indicate any assumptions you made in your answer to this question.
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Tutorials in Introductory Physics
- 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_forwardReview. 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_forwardA factory needs to move packages from one level to another using a ramp. They want to choose a material that has a specific coefficient of friction with the packages that will be sliding down the ramp. What problem could occur if the coefficient of friction were too high? A.Packages would go too fast and could break at the end of the ramp. B.Packages could slow down too quickly and stop before the end of the ramp. C.Packages could break the ramp because gravity would increase. D.Packages could bounce off the ramp because normal force would increase.arrow_forward
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- V1 Refer to Figure the brakes are released. The coefficient of kinetic friction between the tires and the road is 0.7. A truck is traveling at 31 m/s when the brakes are fully applied causing the wheels to skid for 3 seconds and then What is the final speed of the truck in units of m/s ? O 10.40 O 7.40 O 13.40 O 4.40arrow_forwardQuestion 1 A medium-size catapult launches 5-kg steel spheres as in Figure Q1. The launch speed is given as 30 m/s, the launch angle is 35° above horizontal, and the launch position is 2 meters above the ground level. A 2.5-meter concrete wall is positioned 49 meters from the release point on a sloped tarmac as in Figure Q1. Assume constant gravitational acceleration and no aerodynamic drag i. Identify the height of the additional structure required to be installed on top of the wall in order to block the steel sphere from passing through the wall. Show all the important calculations to justify your answer. ii. Calculate the time duration of the flight and the position coordinate of first impact for the steel sphere when it hits the ground vo = 30 m/s CorConcrete wall 2.5 m 0 = 35° 6 m on. 2/2021 2 m 40 m t+ 9marrow_forwardAn empty sled of mass 25 kg slides down a muiddy hill with a constant speed of 2.4 m/s The slope of the hill is inclined at an angle of 15 degrees with the horizontal. a. Calculate the frictional force on the sled as it slides down the slope b.Calculate the coefficient of friction between the sled and the muddy surface of the slope c. The sled reaches the bottom of the slope and continues of horizontal ground. Assume the same coefficient of friction. In terms of velocity and acceleration, describe the motion of the sled as it travels on horizontal ground.arrow_forward
- * for ce of friction is I57 N A 32 kg block sits on a table. This block is attached by a string to a second block that hangs. The string runs over a pulley, as shown below. What is the maximum mass of the hanging block that will allow the 32 kg block to remain stationary? 10. 32Kgarrow_forwardPhysics question: Background information this problem concerns the concept of tension in a rope. Co spider a rope subjected to a pulling force on its two ends. The rope is stationary. An arbitrary point P divides the rope into a left-hand segment L and a right-hand segment R. PART 1: the actual question: now imagine two points, Q and P , that divide the rope into segments L, M, and R. The rope remains stationary. Assume that segments L exerts a force magnitude FLM on segment M. What is the magnitude FRM of the force exerted by segment R on segment M? PART 2 now consider a rope that, unlike those usually studied in mechanics problem, actually has a mass m. The tension at the right end of this rope is T2 and that at the left end is T1 . The rope has an acceleration a rope to the right. Complete the following equation for the force on the section of the rope of inertia m, taking the positive direction to be to the right . Make sure the answers are in terms of T1, T2, and constant such…arrow_forward4. The 2000 kg cable car shown in figure descends a 200m high hill. In addition to its brakes, the cable car controls its speed by pulling an 1800 kg counterweight up the other side of the hill. Friction is negligible. a. How much braking force does the cable car need to descend at constant speed? b. 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? 30⁰ 200 m Counterweight 20°arrow_forward
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