21. Which of the following statements is/are TRUE about friction? * I. Static friction is always greater than kinetic friction. II. Friction only exists when an object is moving on a surface. II. Friction opposes all the forces acting on a moving object. A. I B. I, II C. II, II D. All of the statements O E. None of the statements

21. Which of the following statements is/are TRUE about friction? * I. Static friction is always greater than kinetic friction. II. Friction only exists when an object is moving on a surface. II. Friction opposes all the forces acting on a moving object. A. I B. I, II C. II, II D. All of the statements O E. None of the statements

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 63AP: A box rests on the back of a truck. The coefficient of static friction between the box and the bed...

See similar textbooks

Similar questions

A box rests on the back of a truck. The coefficient of static friction between the box and the bed of the truck is 0.800. (a) When the truck accelerates forward, what force accelerates the box? (b) Find the maximum acceleration the truck can have before the box slides.
A Suppose you place a block of mass M on a plane inclined at an angle . Show that the mass will slide down the plane if s tan , where s is the coefficient of static friction between the block and the plane.
A person holds a ball in her hand, (a) Identify all the external forces acting on the ball and the Newton's third-law reaction force to each one. (b) If the ball is dropped, what force is exerted on it while it is falling? Identify the reaction force in this case. (Ignore air resistance.)
Unreasonable Results A 75.0-kg man stands on a bathroom scale in an elevator that accelerates from rest to 30.0 m/s in 2.00 s. (a) Calculate the scale reading in newtons and compare it with his weight. (The scale exerts an upward force on him equal to its reading.) (b) What is unreasonable about the result? (c) Which premise is unreasonable, or which premises are inconsistent?
When you learn to drive, you discover that you need to up slightly on the brake pedal as you come to a stop or the car will stop with a jerk. Explain this in terms of the relationship between static and friction.
A weight lifter stands on a bathroom scale. (a) As she pumps a barbell up and down, what happens to the reading on the scale? (b) Suppose she is strong enough to actually throw the barbell upward. How does the reading on the scale vary now?
When you learn to drive, you discover that you need to let up slightly on the brake pedal as you come to a stop or the car will stop with a jerk. Explain this in terms of the relationship between static and kinetic friction.
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?
A horse is harnessed to a sled having a mass of 236 kg, including supplies. The horse must exert a force exceeding 1 240 N at an angle of 35.0 in order to get the sled moving. Treat the sled as a point particle, (a) Calculate the normal force on the sled when the magnitude of the applied force is 1 240 N. (b) Find the coefficient of static friction between the sled and the ground beneath it. (c) Find the static friction force when the horse is exerting a force of 6.20 102 N on the sled at the same angle.
Review. A student, along with her backpack on the floor next to her, is in an elevator that is accelerating upward with acceleration a. The student gives her backpack a quick kick at t = 0, imparting to it speed v and causing it to slide across the elevator floor. At time t, the backpack hits the opposite wall a distance L away from the student. Find the coefficient of kinetic friction k between the backpack and the elevator floor.
A setup similar to the one shown in Figure P5.38 is often used in hospitals to support and apply a horizontal traction force to an injured leg. (a) Determine the force of tension in the rope supporting the leg. (b) What is the traction force exerted to the right on the leg?
Which statement is correct? (a) Net force causes motion. (b) Net force causes change in motion. Explain your answer and give an example.