College Physics: A Strategic Approach (4th Edition)
4th Edition
ISBN: 9780134609034
Author: Randall D. Knight (Professor Emeritus), Brian Jones, Stuart Field
Publisher: PEARSON
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Chapter 4, Problem 74MSPP
If your car is stuck in the mud and you don’t have a winch to pull it out, you can use a piece of rope and a tree to do the trick. First, you tie one end of the rope to your car and the other to a tree, then pull as hard as you can on the middle of the rope, as shown in Figure P4.68 a. This technique applies a force to the car much larger than the force that you can apply directly. To see why the car experiences such a large force, look at the forces acting on the center point of the rope, as shown in Figure P4.68 b. The sum of the forces is zero, thus the tension is much greater than the force you apply. It is this tension force that acts on the car and, with luck, pulls it free.
Figure P4.68
68. The sum of the three forces acting on the center point of the rope is assumed to be zero because
A. This point has a very small mass.
B. Tension forces in a rope always cancel.
C. This point is not accelerating.
D. The angle of deflection is very small.
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Draw a diagram of the situation and label the givens in the problem: The cart's mass and the hanger's mass. Also label the direction of the cart and hanger's acceleration.
Draw two force diagrams. One for the cart and one for the hanger. You can treat the track as frictionless. Remember that the force in the string will be the same throughout the entire string.
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If your car is stuck in the mud and you don’t have a winch to pull it out, you can use a piece of rope and a tree to do the trick. First, you tie one end of the rope to your car and the other to a tree, then pull as hard as you can on the middle of the rope, as shown in P4.74a. This technique applies a force to the car much larger than the force that you can apply directly. To see why the car experiences such a large force, look at the forces acting on the center point of the rope, as shown in P4.74b. The sum of the forces is zero, thus the tension is much greater than the force you apply. It is this tension force that acts on the car and, with luck, pulls it free.
Suppose your efforts work, and the car begins to move forward out of the mud. As it does so, the force of the car on the rope isA. Zero.B. Less than the force of the rope on the car.C. Equal to the force of the rope on the car.D. Greater than the force of the rope on the car.
Chapter 4 Solutions
College Physics: A Strategic Approach (4th Edition)
Ch. 4 - If an object is not moving, does that mean that...Ch. 4 - An object moves in a straight line at a constant...Ch. 4 - If you know all of the forces acting on a moving...Ch. 4 - Three arrows are shot horizontally. They have left...Ch. 4 - Prob. 5CQCh. 4 - Internal injuries in vehicular acci-dents may be...Ch. 4 - Heres a great everyday use of the physics...Ch. 4 - Prob. 8CQCh. 4 - Suppose you are an astronaut in deep space, far...Ch. 4 - Jonathan accelerates away from a stop sign. His...
Ch. 4 - Prob. 11CQCh. 4 - Prob. 12CQCh. 4 - Josh and Taylor, standing face-to-face on...Ch. 4 - A person sits on a sloped hillside. Is it ever...Ch. 4 - Walking without slipping requires a static...Ch. 4 - Figure 4.30 b showed a situation in which the...Ch. 4 - Prob. 17CQCh. 4 - Prob. 18CQCh. 4 - The tire on this drag racer is severely twisted:...Ch. 4 - Suppose that, while in a squatting position, you...Ch. 4 - A block has acceleration a when pulled by a...Ch. 4 - A 5.0 kg block has an acceleration of 0.20 m/s2...Ch. 4 - Tennis balls experience a large drag force. A...Ch. 4 - A group of students is making model cars that will...Ch. 4 - A person gives a box a shove so that it slides up...Ch. 4 - Prob. 26MCQCh. 4 - As shown in the chapter, scallops use jet...Ch. 4 - Prob. 28MCQCh. 4 - Prob. 29MCQCh. 4 - Dave pushes his four-year-old son Thomas across...Ch. 4 - Figure Q4.29 shows block A sitting on top of block...Ch. 4 - Whiplash injuries during an automobile accident...Ch. 4 - An automobile has a head-on collision. A passenger...Ch. 4 - In a head-on collision, an infant is much safer in...Ch. 4 - Problems 4 through 6 show two forces acting on an...Ch. 4 - Problems 4 through 6 show two forces acting on an...Ch. 4 - Problems 4 through 6 show two forces acting on an...Ch. 4 - Prob. 7PCh. 4 - Prob. 8PCh. 4 - A baseball player is sliding into second base....Ch. 4 - A jet plane is speeding down the runway during...Ch. 4 - A skier is sliding down a 15 slope. Friction is...Ch. 4 - A falcon is hovering above the ground, then...Ch. 4 - Figure P4.13 shows an acceleration-versus-force...Ch. 4 - A constant force applied to object A causes it to...Ch. 4 - A compact car has a maximum acceleration of 4.0...Ch. 4 - Prob. 16PCh. 4 - A constant force is applied to an object, causing...Ch. 4 - A man pulling an empty wagon causes it to...Ch. 4 - Prob. 19PCh. 4 - Scallops eject water from their shells to provide...Ch. 4 - Figure P4.21 shows an objects...Ch. 4 - Prob. 22PCh. 4 - Two children fight over a 200 g stuffed bear. The...Ch. 4 - Prob. 24PCh. 4 - Prob. 25PCh. 4 - Prob. 26PCh. 4 - Prob. 27PCh. 4 - Prob. 28PCh. 4 - Problems 27 through 29 show a free-body diagram....Ch. 4 - Problems 27 through 29 show a free-body diagram....Ch. 4 - Problems 27 through 29 show a free-body diagram....Ch. 4 - Prob. 32PCh. 4 - Problems 30 through 38 describe a situation. For...Ch. 4 - Problems 30 through 38 describe a situation. For...Ch. 4 - Problems 30 through 38 describe a situation. For...Ch. 4 - Problems 30 through 38 describe a situation. For...Ch. 4 - Problems 30 through 38 describe a situation. For...Ch. 4 - Prob. 38PCh. 4 - Problems 30 through 38 describe a situation. For...Ch. 4 - Problems 30 through 38 describe a situation. For...Ch. 4 - Prob. 41PCh. 4 - Prob. 42PCh. 4 - Three ice skaters, numbered 1, 2, and 3, stand in...Ch. 4 - A girl stands on a sofa. Identify all the...Ch. 4 - A car is skidding to a stop on a level stretch of...Ch. 4 - Squid use jet propulsion for rapid escapes. A...Ch. 4 - Prob. 47GPCh. 4 - Prob. 48GPCh. 4 - Prob. 49GPCh. 4 - Prob. 50GPCh. 4 - Prob. 51GPCh. 4 - Prob. 52GPCh. 4 - Problems 49 through 61 describe a situation. For...Ch. 4 - Problems 49 through 61 describe a situation. For...Ch. 4 - Problems 49 through 61 describe a situation. For...Ch. 4 - Prob. 56GPCh. 4 - Prob. 57GPCh. 4 - Problems 49 through 61 describe a situation. For...Ch. 4 - Problems 49 through 61 describe a situation. For...Ch. 4 - Prob. 60GPCh. 4 - Problems 49 through 61 describe a situation. For...Ch. 4 - Problems 49 through 61 describe a situation. For...Ch. 4 - Problems 49 through 61 describe a situation. For...Ch. 4 - Problems 49 through 61 describe a situation. For...Ch. 4 - A bag of groceries is on the back seat of your car...Ch. 4 - A car has a mass of 1500 kg. If the driver applies...Ch. 4 - Prob. 67GPCh. 4 - Prob. 69GPCh. 4 - Prob. 70GPCh. 4 - Prob. 71GPCh. 4 - The froghopper, champion leaper of the insect...Ch. 4 - A beach ball is thrown straight up, and some time...Ch. 4 - If your car is stuck in the mud and you dont have...Ch. 4 - Prob. 75MSPPCh. 4 - Prob. 76MSPPCh. 4 - If your car is stuck in the mud and you don't have...
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