The 1900 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 1850 kg counterweight up the other side of the hil. The rolling friction of both the cable car and the counterweight are negligible. (Elgure 1) • Part A How much braking force does the cable car need to descend at constant speed? Express your answer with the appropriate units. Value Units Submit Request Answer • Part 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? Express your answer with the appropriate units. Value Units Submit Request Answer

The 1900 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 1850 kg counterweight up the other side of the hil. The rolling friction of both the cable car and the counterweight are negligible. (Elgure 1) • Part A How much braking force does the cable car need to descend at constant speed? Express your answer with the appropriate units. Value Units Submit Request Answer • Part 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? Express your answer with the appropriate units. Value Units Submit Request Answer

Physics for Scientists and Engineers with Modern Physics

10th Edition

ISBN:9781337553292

Author:Raymond A. Serway, John W. Jewett

Publisher:Raymond A. Serway, John W. Jewett

Chapter5: The Laws Of Motion

Section: Chapter Questions

Problem 40AP: A 1.00-kg glider on a horizontal air track is pulled by a string at an angle . The taut string runs...

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A freight train consists of two 8.00 × 105 -kg engines and 45 cars with average masses of 5.50 × 105 kg. (a) What force must each engine exert backward on the track to accelerate the train at a rate of 5.00 × 10−2 m/s2 if the force of friction is 7.50 × 105 N, assuming the engines exert identical forces? This is not a large frictional force for such a massive system. Rolling friction for trains is small, and consequently, trains are very energy-efficient transportation systems. (b) What is the force in the coupling between the 37th and 38th cars (this is the force each exerts on the other), assuming all cars have the same mass and that friction is evenly distributed among all of the cars and engines?
1. Which of the following is TRUE about an object with constant acceleration? a. A constant force is applied to the objectb. The object might reach numerous max velocityc. The object might have zero acceleration d. The object might reach zero velocity e. All of the above 2. You let a ball roll on a rough surface with coefficient of kinetic friction 0.54. Which of the following statement is TRUE about the ball? a. The ball is being acted upon by conservative forces onlyb. The ball's mechanical energy is conservedc. The ball's mechanical energy is not conservedd. The ball is being acted upon by non-conservative forces onlye. None of the above
An object with mass m = 34 kg is pushed with 452 N of force to be moved across a distance of 4.6 m on a surface with friction. Initially the object is moving at vi = 0.82 m/s and after being moved across 4.6 m, the final speed is 2.5 m/s. What is the magnitude of the frictional force acting on the object in the unit of N?
A 63.0 kgkg parachutist falling vertically at a speed of 6.50 m/sm/s hits the ground, which brings him to a complete stop in a distance of 0.87 mm (roughly half of his height). 1) Assuming constant acceleration after his feet first touch the ground, what is the average force exerted on the parachutist by the ground? Express your answer with the appropriate units.
Consider the Atwood machine shown in the figure, where m1 = 2.00 kg and m2 = 5.00 kg. The system starts at rest, then the sphere is given a quick push downward, giving it an initial speed of 2.45 m/s. Assume the pulley and cord are massless, and the cord is inextensible. Neglect friction. (a)Through what distance (in m) will m1 descend? b)What is the velocity (in m/s) of m1 after 1.80 s? magnitude
Consult Multiple Concept Example 10 in preparation for this problem. Traveling at a speed of 12.4 m/s, the driver of an automobile suddenly locks the wheels by slamming on the brakes. The coefficient of kinetic friction between the tires and the road is 0.730. What is the speed of the automobile after 1.25 s have elapsed? Ignore the effects of air resistance. Number Type your answer here Units Choose your answer here
An automobile driver traveling down an 8% grade slams on his brakes and skids 30 m before hitting a parked car. A lawyer hires an expert who measures the coefficient of kinetic friction between the tires and road to be k = 0.45. Is the lawyer correct to accuse the driver of exceeding the 25-MPH speed limit? Explain.
A 1.00-kg glider on a horizontal air track is pulled by a string at an angle . The taut string runs over a pulley and is attached to a hanging object of mass 0.500 kg as shown in Figure P5.40. (a) Show that the speed vx of the glider and the speed vy of the hanging object are related by vx = uvy, where u = z(z2 h02)1/2. (b) The glider is released from rest. Show that at that instant the acceleration ax of the glider and the acceleration ay of the hanging object are related by ax = uay. (c) Find the tension in the string at the instant the glider is released for h0 = 80.0 cm and = 30.0. Figure P5.40
Why is the following situation impossible? A 1.30-kg toaster is not plugged in. The coefficient of static friction between the toaster and a horizontal countertop is 0.350. To make the toaster start moving, you carelessly pull on its electric cord. Unfortunately, the cord has become frayed from your previous similar actions and will break if the tension in the cord exceeds 4.00 N. By pulling on the cord at a particular angle, you successfully start the toaster moving without breaking the cord.
A makeshift sign hangs by a wire that is extended over an ideal pulley and is wrapped around a large potted plant on the roof as shown in Figure P6.10. When first set up by the shopkeeper on a sunny and dry day, the sign and the pot are in equilibrium. Is it possible that the sign falls to the ground during a rainstorm while still remaining connected to the pot? What would have to be true for that to be possible? FIGURE P6.10 Problems 10 and 11.
In the situation described in Problem 45 and Figure P4.45, the masses of the rope, spring balance, and pulley are negligible. Nicks feet are not touching the ground. (a) Assume Nick is momentarily at rest when he stops pulling down on the rope and passes the end of the rope to another child, of weight 440 N, who is standing on the ground next to him. The rope does not break. Describe the ensuing motion. (b) Instead, assume Nick is momentarily at rest when he ties the end of the rope to a strong hook projecting from the tree trunk. Explain why this action can make the rope break. Figure P4.45 Problems 45 and 46.
A hand tractor of mass 1000kg is attached by means of a horizontal, massless chain to a log whose mass is 400kg. The tension in the chain is 2000N, and the backward force of friction exerted by the ground on the log is 800N. How far will the log move in 3s, starting from rest? ANS. 3m/s², 13.5m.