At time t = Os, the 50 N crate is sitting at rest on the floor. %3D There is a coefficient of static friction Hg=0.400 between the floor and the crate. There is a coefficient of static friction Hy=0.200 between the floor and the crate. An applied force F = 12.0 N is acting to on the box to the right. %3D A) What is the value of the frictional force the box feels at timet = 0? f = B) What is the value of the frictional force the box feels at time t > 0? Consider the exact same situation, except the applied force is F=24.0 N. C) What is the value of the frictional force the box feels at time t = 0? f =

At time t = Os, the 50 N crate is sitting at rest on the floor. %3D There is a coefficient of static friction Hg=0.400 between the floor and the crate. There is a coefficient of static friction Hy=0.200 between the floor and the crate. An applied force F = 12.0 N is acting to on the box to the right. %3D A) What is the value of the frictional force the box feels at timet = 0? f = B) What is the value of the frictional force the box feels at time t > 0? Consider the exact same situation, except the applied force is F=24.0 N. C) What is the value of the frictional force the box feels at time t = 0? f =

College Physics

10th Edition

ISBN:9781285737027

Author:Raymond A. Serway, Chris Vuille

Publisher:Raymond A. Serway, Chris Vuille

Chapter4: The Laws Of Motion

Section: Chapter Questions

Problem 60AP: (a) What is the minimum force of friction required to hold the system of Figure P4.74 in...

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A block of ice (m = 15.0 kg) with an attached rope is at rest on a frictionless surface. You pull the block with a horizontal force of 95.0 N for 1.54 s. a. Determine the magnitude of each force acting on the block of ice while you are pulling. b. With what speed is the ice moving after you are finished pulling? Repeat Problem 71, but this time you pull on the block at an angle of 20.0.
A force F applied to an object of mass m1 produces an acceleration of 3.00 m/s2. The same force applied to a second object of mass m2 produces an acceleration of 1.00 m/s2. (a) What is the value of the ratio m1/m2? (b) If m1 and m2 are combined into one object, find its acceleration under the action of the force F.
Two blocks, each of mass m, are hung from the ceiling of an elevator as in Figure P4.33. The elevator has an upward acceleration a. The strings have negligible mass. (a) Find the tensions T1 and T2 in the upper and lower strings in terms of m, a, and g. (b) Compare the two tensions and determine which string would break first if a is made sufficiently large. (c) What are the tensions if the cable supporting the elevator breaks? Figure P4.33 Problems 33 and 34.
Starting from rest, a rectangular toy block with mass 300 g slides in 1.30 s all the way across a table 1.20 m in length that Zak has tilted at an angle of 42.0 to the horizontal. a. What is the magnitude of the acceleration of the toy block? b. What is the coefficient of kinetic friction between the block and the table? c. What are the magnitude and direction of the friction force acting on the block? d. What is the speed of the block when it is at the end of the table, having slid a distance of 1.20 m?
(a) An elevator of mass m moving upward has two forces acting on it: the upward force of tension in the cable and the downward force due to gravity. When the elevator is accelerating upward, which is greater. T or w? (b) When the elevator is moving at a constant velocity upward, which is greater. T or w2 (c) When the elevator is moving upward, but the acceleration is downward, which is greater. T or w? (d) Let the elevator have a mass of 1500 kg and an upward acceleration of 2.5 m/s2. Find T. Is your answer consistent with the answer to part (a)? (e) The elevator of part (d) now moves with a constant upward velocity of 10 m/s. Find T. Is your answer consistent with your answer to part (b)? (f) Having initially moved upward with a constant velocity, the elevator begins to accelerate downward at 1.50 m/s2. Find T Is your answer consistent with your answer to part (c)?
Give reasons for the answers to each of the following questions: (a) Clan a normal force be horizontal? (b) Can a normal force be directed vertically downward? (c) Consider a tennis ball in contact with a stationary floor and with nothing else. Can the normal force be different in magnitude from the gravitational force exerted on the ball? (d) Can the force exerted by the floor on the hall be different in magnitude from the force the ball exerts on the floor?
(a) What is the minimum force of friction required to hold the system of Figure P4.74 in equilibrium? (b) What coefficient of static friction between the 100.-N block and the table ensures equilibrium? (c) If the coefficient of kinetic friction between the 100.-N block and the table is 0.250, what hanging weight should replace the 50.0-N weight to allow the system to move at a constant speed once it is set in motion? Figure P4.74
An object of mass M is held in place by an applied force F and a pulley system as shown in Figure P4.43. The pulleys are massless and frictionless. (a) Draw diagrams showing the forces on each pulley. Find (b) the tension in each section of rope, T1, T2, T3, T4, and T5 and (c) the magnitude of F. Figure P4.43 44. Any device that allows you to increase the force you exert is a kind of machine. Some machines, such as the prybar or the inclined plane, are very simple. Some machines do not even look like machines. For example, your car is stuck in the mud and you cant pull hard enough to get it out. You do, however, have a long cable that you connect taut between your front bumper and the trunk of a stout tree. You now pull sideways on the cable at its midpoint, exerting a force f. Each half of the cable is displaced through a small angle from the straight line between the ends of the cable. (a) Deduce an expression for the force acting on the car. (b) Evaluate the cable tension for the case where = 7.00 and f = 100 N.
Consider the three connected objects shown in Figure P5.43. Assume first that the inclined plane is frictionless and that the system is in equilibrium. In terms of m, g, and , find (a) the mass M and (b) the tensions T1 and T2. Now assume that the value of M is double the value found in part (a). Find (c) the acceleration of each object and (d) the tensions T1 and T2. Next, assume that the coefficient of static friction between m and 2m and the inclined plane is s and that the system is in equilibrium. Find (e) the maximum value of M and (f) the minimum value of M. (g) Compare the values of T2 when M has its minimum and maximum values. Figure P5.43
(a) An elevator of mass m moving upward has two forces acting on it: the upward force of tension in the cable and the downward force due to gravity. When the elevator is accelerating upward, which is greater, T or w? (b) When the elevator is moving at a constant velocity upward, which is greater, T or w? (c) When the elevator is moving upward, but the acceleration is downward, which is greater, T or w? (d) Let the elevator have a mass of 1 500 kg and an upward acceleration of 2.5 m/s2. Find T. Is your answer consistent with the answer to part (a)? (e) The elevator of part (d) now moves with a constant upward velocity of 10 m/s. Find T. Is your answer consistent with your answer to part (b)? (f) Having initially moved upward with a constant velocity, the elevator begins to accelerate downward at 1.50 m/s2. Find T. Is your answer consistent with your answer to part (c)?
A worker is attempting to lift a 55.0-kg palette of bricks resting on the ground by means of a rope attached to a pulley. a. Before the worker pulls on the rope, what is the force exerted by the ground on the palette? b. The worker exerts a force of 295 N downward on his end of the rope. What is the force exerted by the ground on the palette? c. If the worker doubles the downward force, what is the force exerted by the ground on the palette?
(a) Find the tension in each cable supporting the 6.00 102-N cat burglar in Figure P4.35. (b) Suppose the horizontal cable were reattached higher up on the wall. Would the tension in the other cables increase, decrease, or stay the same? Why? Figure P4.35