Concept explainers
Two blocks tied together by a horizontal string are being pulled across the table by a horizontal force of 46 N, as shown in the diagram below. The 3-kg block has a 6-N frictional force exerted on it by the table, and the 7-kg block has an 8-N frictional force acting on it.
- a. What is the net force acting on the entire two-block system?
- b. What is the acceleration of this system?
- c. What force is exerted on the 3-kg block by the connecting string? (Consider only the forces acting on this block. Its acceleration is the same as that of the entire system.)
- d. Find the net force acting on the 7-kg block and calculate its acceleration. How does this value compare to that found in part b?
(a)
The net force acting on the entire two-block system.
Answer to Problem 5SP
The net force acting on the entire two-block system is
Explanation of Solution
Given info: The horizontal force acting on
Write the expression for the net horizontal force.
Here,
Total force on the left direction is the sum of
That is,
Substitute
Conclusion:
Thus, the net force acting on the entire two-block system is
(b)
The acceleration of the system.
Answer to Problem 5SP
The acceleration of the system is
Explanation of Solution
Given info: The masses of the blocks are
Write the expression for the acceleration of the horizontal acceleration of the block.
Here,
Total mass of the system is
Substitute
Conclusion:
Thus, the acceleration of the system is
(c)
The force acting on the
Answer to Problem 5SP
The force acting on the
Explanation of Solution
Given info: The horizontal force acting on
Let
Write the expression for the net force on
Here,
Substitute
This net force is acting along the direction of acceleration. That is, along the right direction.
Write the expression for the net force on the
Here,
The negative sign indicate that the force of tension is along the right direction whereas the
Substitute
Therefore, the force acting on the
Conclusion:
Thus, the force acting on the
(d)
The net force and acceleration of
Answer to Problem 5SP
The net force on the
Explanation of Solution
Given info: The horizontal force acting on
Write the expression for the net force on the
Here,
Substitute
Write the expression for the net acceleration on
Here,
Substitute
This is same as the net acceleration obtained in part
Conclusion:
Thus, the net force on the
Want to see more full solutions like this?
Chapter 4 Solutions
Physics of Everyday Phenomena
- A block of mass 3m is placed on a frictionless horizontal surface, and a second block of mass m is placed on top of the first block. The surfaces of the blocks are rough. A constant force of magnitude F is applied to the first block as in Figure P4.68. (a) Construct free-body diagrams for each block. (b) Identify the horizontal force that causes the block of mass m to accelerate. (c) Assume that the upper block does not slip on the lower block, and find the acceleration of each block in terms of m and F. Figure P4.68arrow_forwardWhen a 1.50-kg dress hangs midway from a taut clothesline stretched between two poles planted 7.50 m apart, the clothesline is seen to sag 0.0500 m. a. Draw a free-body diagram of the dress. b. What is the tension produced on the clothesline by the dress? Assume the clothesline is massless.arrow_forwardDrawing Free-Body Diagrams A ball of mass m hangs at rest, suspended by a sting. (a) Sketch all forces. (b) Draw the free-body diagram for the ball.arrow_forward
- A person holds a ball in her hand. (a) Identify all the external forces acting on the ball and the Newtons 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.)arrow_forwardSuppose two children push horizontally, but in exactly opposite directions, on a third child in a wagon. The first child exerts a force of 75.0 N, the second exerts a force of 90.0 N, friction is 12.0 N, and the mass of the third child plus wagon is 23.0 kg. (a) What is the system of interest if the acceleration of the child in the wagon is to be calculated? (See the free-body diagram.) (b) Calculate the acceleration. (c) What would the acceleration be if friction were 15.0 N?arrow_forwardWhich statement is correct? (a) Net force causes motion. (b) Net force causes change in motion. Explain your answer and give an example.arrow_forward
- For all three situations, find the magnitude and direction of the tension force(s) exerted on Rochelle. If not enough information is given, say so. Explain your answers. a. Rochelle and Buddy pull on opposite ends of rope. The tension force exerted on Buddy is 15 N and is directed toward Rochelle. b. Now, one end of the rope is tied to a sturdy pole and Rochelle pulls on the other end. The tension force on the pole is 15 N directed toward Rochelle. c. Finally, Rochelle holds one rope in her left hand, and the other end of that rope is pulled by Joe. She holds another rope in her right hand, and the other end of that rope is pulled by Buddy. Both Buddy and Joe experience a 15-N force directed toward Rochelle.arrow_forwardThe wheels of a midsize car exert a force of 2100 N backward on the road to accelerate the car in the forward direction. If the force of friction including air resistance is 250 N and the acceleration of the car is 1.80 m/s2, what is the mass of the car plus its occupants? Explicitly show how you follow the steps in the Problem-Solving Strategy for Newton's laws of motion. For this situation, draw a free-body diagram and write the net force equation.arrow_forwardWhen 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.arrow_forward
- College PhysicsPhysicsISBN:9781285737027Author:Raymond A. Serway, Chris VuillePublisher:Cengage LearningGlencoe Physics: Principles and Problems, Student...PhysicsISBN:9780078807213Author:Paul W. ZitzewitzPublisher:Glencoe/McGraw-HillPhysics for Scientists and Engineers: Foundations...PhysicsISBN:9781133939146Author:Katz, Debora M.Publisher:Cengage Learning
- University Physics Volume 1PhysicsISBN:9781938168277Author:William Moebs, Samuel J. Ling, Jeff SannyPublisher:OpenStax - Rice UniversityCollege PhysicsPhysicsISBN:9781938168000Author:Paul Peter Urone, Roger HinrichsPublisher:OpenStax CollegePrinciples of Physics: A Calculus-Based TextPhysicsISBN:9781133104261Author:Raymond A. Serway, John W. JewettPublisher:Cengage Learning