A ball is hanging from a long string that is tied to the ceiling of a train car traveling eastward on horizontal tracks. An observer inside the train car sees the ball hang motionless. Draw a clearly labeled free-body diagram for the ball if (a) the train has a uniform velocity and (b) the train is speeding up uniformly. Is the net force on the ball zero in either case? Explain.

A ball is hanging from a long string that is tied to the ceiling of a train car traveling eastward on horizontal tracks. An observer inside the train car sees the ball hang motionless. Draw a clearly labeled free-body diagram for the ball if (a) the train has a uniform velocity and (b) the train is speeding up uniformly. Is the net force on the ball zero in either case? Explain.

Principles of Physics: A Calculus-Based Text

5th Edition

ISBN:9781133104261

Author:Raymond A. Serway, John W. Jewett

Publisher:Raymond A. Serway, John W. Jewett

Chapter4: The Laws Of Motion

Section: Chapter Questions

Problem 28P: An object of mass m1 = 5.00 kg placed on a frictionless, horizontal table is connected to a string...

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M1 is connected to M2 with a rigid string. Both sits on a leveled ground of uk=0.25 with M3 sitting on top of M2. When a force F 25 N pulls on M1 forward with an angle 30.0 degrees with respect to the ground, all three blocks move at the same acceleration. (M1= 3.0 kg, M2=2.0 kg, M3=1.0 kg) a. draw a free body diagram of each block, b. what is the normal force and friction on M1 ? c. what is the acceleration of the system (M1+M2+M3)? d. use work and Kinetic theory to find the speed of the system at the time all blocks have traveled a displacement of 5.0 m.
A block with a mass of m = 45 kg rests on a frictionless surface and is subject to two forces acting on it. The first force is directed in the negative x-direction with a magnitude of F1. The second has a magnitude of F2 and acts on the body at an angle θ = 17° measured from horizontal, as shown. 1) Write an expression for the magnitude of the normal force, FN, acting on the block, in terms of F2 and the other variables of the problem. Assume that the surface it rests on is rigid. 2) The two forces change such that F1 = 9.5 N and F2 = 23.5 N. Based on this change, the block may no longer be in static equilibrium. Find the block's acceleration in the x-direction, ax, in meters per second squared.
A light rope is attached to a block with mass 4.00 kg that rests on a frictionless,horizontal surface. The horizontal rope passes over a frictionless, massless pulley, and ablock with mass m is suspended from the other end. When the blocks are released, thetension in the rope is 10.0 N. (a) Draw two free-body diagrams, one for the 4.00-kg blockand one for the block with mass m. (b) What is the acceleration of either block? (c) Findthe mass m of the hanging block. (d) How does the tension compare to the weight of thehanging block?
A rocket of mass 2.8 × 106 kg is launched straight upward into the sky. Its thrust force vector has a magnitude of 7.78 × 107 N . Note that it experiences a weight force due to gravity. Ignore air resistance. (a.) Draw a free-body diagram for the rocket. (b.) Using the forces you identified in your free-body diagram, apply Newton’s Second Law (in component form) to find the x- and y-components, ax and ay, of the rocket’s acceleration vector. (c.) What, then, is the magnitude and direction of the rocket’s acceleration?
A 15.0N force pushes a piece of brass to the right. It took 4.0 seconds for the piece of brass to slide 35.0 meters horizontally on a steel surface at a starting velocity of 5.0 m/s. The coefficient of kinetic friction between the brass and steel is 0.37. a). Draw the free-body diagram of the piece of brass.b). What is the acceleration of the piece of brass within the given time frame?c). What is the mass of the piece of brass?
A block with mass of m1 = 2 kg is placed on top of a block with a mass m2 = 4 kg. A horizontal force of F=60 N is applied tothe block m2, and the block m1 is tied to the wall. Thecoefficient of kinetic friction between all surfaces is0.400. (a) Draw a free-body diagram for each block andidentify the action–reaction forces between the blocks. (b)Determine the tension in the string and the magnitude of the acceleration of the block m2. ( g=9.8 m/s2 )
What If? How would your answers to parts (a) and (b) of this problem change if the 2.0 kg block was now stacked on top of the 1.0 kg block? Assume that the 2.0 kg block sticks to and does not slide on the 1.0 kg block when the system is accelerated. (Enter the acceleration in m/s2 to the right and the tension in N.)
Two blocks of masses m1 and m2 (m1 m2) are placed on a frictionless table in contact with each other. A horizontal force of magnitude F is applied to the block of mass m1 in Figure P4.62. (a) If P is the magnitude of the contact force between the blocks, draw the free-body diagrams for each block. (b) What is the net force on the system consisting of both blocks? (c) What is the net force acting on m1? (d) What is the net force acting on m2? (e) Write the x-component of Newtons second law for each block. (f) Solve the resulting system of two equations and two unknowns, expressing the acceleration a and contact force P in terms of the masses and force. (g) How would the answers change if the force had been applied to m2 instead? (Hint: use symmetry; dont calculate!) Is the contact force larger, smaller, or the same in this case? Why? Figure P4.62
Two blocks of masses m1 and m2 (m1 m2) are placed on a frictionless table in contact with each other. A horizontal force of magnitude F is applied to the block of mass m1 in Figure P4.62. (a) If P is the magnitude of the contact force between the blocks, draw the free-body diagrams for each block. (b) What is the net force on the system consisting of both blocks? (c) What is the net force acting on m1? (d) What is the net force acting on m2? (e) Write the x-component of Newtons second law for each block. (f) Solve the resulting system of two equations and two unknowns, expressing the acceleration a and contact force P in terms of the masses and force. (g) How would the answers change if the force had been applied to m2 instead? (Hint: use symmetry; dont calculate!) Is the contact force larger, smaller, or the same in this case? Why? Figure P4.62
A rope with mass m, is attached to a block with mass mb, as in Figure P4.72. Both the rope and the block rest on a horizontal, frictionless surface. The rope does not stretch. The free end of the rope is pulled to the right with a horizontal force F. (a) Draw free-body diagrams for the rope and the block, noting that the tension in the rope is not uniform, (b) Find the acceleration of the system in terms of mb, mT, and F. (c) Find the magnitude of the force the rope exerts on the block, (d) What happens to the force on the block as the ropes mass approaches zero? What can you state about the tension in a light cord joining a pair of moving objects? Figure P4.72
In Example 4.5, we pushed on two blocks on a table. Suppose three blocks are in contact with one another on a frictionless, horizontal surface as shown in Figure P4.49. A horizontal force F is applied to m1. Take m1 = 2.00 kg, m2 = 3.00 kg, m3 = 4.00 kg, and F = 18.0 N. (a) Draw a separate free-body diagram for each block. (b) Determine the acceleration of the blocks. (c) Find the resultant force on each block. (d) Find the magnitudes of the contact forces between the blocks. (e) You are working on a construction project. A coworker is nailing up plasterboard on one side of a light partition, and you are on the opposite side, providing backing by leaning against the wall with your back pushing on it. Every hammer blow makes your back sting. The supervisor helps you put a heavy block of wood between the wall and your back. Using the situation analyzed in parts (a) through (d) as a model, explain how this change works to make your job more comfortable. Figure P4.49
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.