*Problem 2: Angela is pushing a 10kg crate (Crate A) to the right at ả = 2£ . Crate B (5 kg) is to the right of and being pushed by Crate A. m a) Draw FBDS for Crates A and B. Be sure to name the forces based on the "from-to" designation and draw force vectors to scale. b) Identify the Third Law Pairs of forces from your FBDS. c) Use Newton's Second Law to find the force that Angela is applying horizontally to Crate A. (Answer: 30£ N)

*Problem 2: Angela is pushing a 10kg crate (Crate A) to the right at ả = 2£ . Crate B (5 kg) is to the right of and being pushed by Crate A. m a) Draw FBDS for Crates A and B. Be sure to name the forces based on the "from-to" designation and draw force vectors to scale. b) Identify the Third Law Pairs of forces from your FBDS. c) Use Newton's Second Law to find the force that Angela is applying horizontally to Crate A. (Answer: 30£ N)

Physics for Scientists and Engineers: Foundations and Connections

1st Edition

ISBN:9781133939146

Author:Katz, Debora M.

Publisher:Katz, Debora M.

Chapter6: Applications Of Newton’s Laws Of Motion

Section: Chapter Questions

Problem 5PQ

See similar textbooks

Similar questions

An inventive child named Nick wants to reach an apple in a tree without climbing the tree. Sitting in a chair connected to a rope that passes over a frictionless pulley (Fig. P4.45), Nick pulls on the loose end of the rope with such a force that the spring scale reads 250 N. Nicks true weight is 320 N, and the chair weighs 160 N. Nicks feet are not touching the ground. (a) Draw one pair of diagrams showing the forces for Nick and the chair considered as separate systems and another diagram for Nick and the chair considered as one system. (b) Show that the acceleration of the system is upward and find its magnitude. (c) Find the force Nick exerts on the chair. Figure P4.45 Problems 45 and 46. 46. In the situation described in Problem 45 and Figure P4.45, the masses of the rope, spring balance, and pulley are negligible. Nicks feet are not touching the ground. (a) Assume Nick is momentarily at rest when he stops pulling down on the rope and passes the end of the rope to another child, of weight 440 N, who is standing on the ground next to him. The rope does not break. Describe the ensuing motion. (b) Instead, assume Nick is momentarily at rest when he ties the end of the rope to a strong hook projecting from the tree trunk. Explain why this action can make the rope break.
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.)
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.
Measuring coefficients of friction A coin is placed near one edge of a book lying on a table, and that edge of the book is lifted until the coin just slips down the incline as shown in Figure P4.82. The angle of the incline, C, called the critical angle, is measured. (a) Draw a free-body diagram for the coin when it is on the verge of slipping and identify all forces acting on it. Your free-body diagram should include a force of static friction acting up the incline. (b) Is the magnitude of the friction force equal to sn for angles less than C? Explain. What can you definitely say about the magnitude of the friction force for any angle c? (c) Show that the coefficient of static friction is given by s = tan c. (d) Once the coin starts to slide down the incline, the angle can be adjusted to a new value c c such that the coin moves down the incline with constant speed. How does observation enable you to obtain the coefficient of kinetic friction? Figure P4.82
A small steel I-beam (Fig. P6.14) is at rest with respect to the steel surface of a truck. The truck is accelerating with respect to the road. The mass of the I-beam is 5.8 103 kg. a. Draw a free-body diagram for the I-beam. b. What force or forces accelerate the I-beam with respect to the ground? c. The I-beam must remain at rest with respect to the truck. What is the maximum acceleration of the truck? Evaluate your answer. d. On the highway, the truck moves with a constant velocity. Draw a free-body diagram for the I-beam. Compare it with your diagram in part (a). FIGURE P6.14
An inventive child named Nick wants to reach an apple in a tree without climbing the tree. Sitting in a chair connected to a rope that passes over a frictionless pulley (Fig. P5.41), Nick pulls on the loose end of the rope with such a force that the spring scale reads 250 N. Nicks true weight is 320 N, and the chair weighs 160 N. Nicks feet are not touching the ground. (a) Draw one pair of diagrams showing the forces for Nick and the chair considered as separate systems and another diagram for Nick and the chair considered as one system. (b) Show that the acceleration of the system is upward and find its magnitude. (c) Find the force Nick exerts on the chair. Figure P5.41 Problems 41 and 44.
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.
Construct Your Own Problem Consider people pushing a toboggan with four children on it up a snow-covered slope. Construct a problem in which you calculate the acceleration of the toboggan and its load. Include a free-body diagram of the appropriate system of interest as the basis for your analysis. Show vector forces and their components and explain the choice of coordinates. Among the things to be considered are the forces exerted by those pushing, the angle of the slope, and the masses of the toboggan and children.
Shown in Figure 5.4 are four situations in which a force acts on a subject. The subject is labeled in each case. Case 1. A baseball glove stops a vertically falling baseball. Case 2. CASE STUDY A freight train collides with a slopped passenger train. Case 3. A satellite orbits the Earth. For each case, identify the source of the force and the direction of the force. Then state whether a contact force or a field force is involved.
A ball is held in a persons hand. (a) Identify all the external forces acting on the ball and the reaction to each. (b) If the ball is dropped, what force is exerted on it while it is falling? Identify the reaction force in this case. (Neglect 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?
A car is moving forward slowly and is speeding up. A student claims that the car exerts a force on itself or that the cars engine exerts a force on the car. (a) Argue that this idea cannot be accurate and that friction exerted by the road is the propulsive force on the car. Make your evidence and reasoning as persuasive as possible. (b) Is it static or kinetic friction? Suggestions: Consider a road covered with light gravel. Consider a sharp print of the tire tread on an asphalt road, obtained by coating the tread with dust.