Textbook Question
A rubber ball bounces. We'd like to understand how the ball bounces. Draw a free-body diagram of the ball during its contact with the ground. Is there a net force acting on the ball? If so, in which direction?
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Ch 05: Force and Motion
Knight Calc5th EditionPhysics for Scientists and EngineersISBN: 9780137344796
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Table of contents
- Ch 01: Concepts of Motion35
- Ch 02: Kinematics in One Dimension75
- Ch 03: Vectors and Coordinate Systems58
- Ch 04: Kinematics in Two Dimensions60
- Ch 05: Force and Motion23
- Ch 06: Dynamics I: Motion Along a Line53
- Ch 07: Newton's Third Law27
- Ch 08: Dynamics II: Motion in a Plane52
- Ch 09: Work and Kinetic Energy56
- Ch 10: Interactions and Potential Energy50
- Ch 11: Impulse and Momentum56
- Ch 12: Rotation of a Rigid Body71
- Ch 13: Newton's Theory of Gravity52
- Ch 14: Fluids and Elasticity44
- Ch 15: Oscillations55
- Ch 16: Traveling Waves37
- Ch 17: Superposition39
- Ch 18: A Macroscopic Description of Matter53
- Ch 19: Work, Heat, and the First Law of Thermodynamics60
- Ch 20: The Micro/Macro Connection53
- Ch 21: Heat Engines and Refrigerators34
- Ch 22: Electric Charges and Forces40
- Ch 23: The Electric Field39
- Ch 24: Gauss' Law32
- Ch 25: The Electric Potential63
- Ch 26: Potential and Field57
- Ch 27: Current and Resistance42
- Ch 28: Fundamentals of Circuits39
- Ch 29: The Magnetic Field47
- Ch 30: Electromagnetic Induction60
- Ch 31: Electromagnetic Fields and Waves32
- Ch 32: AC Circuits63
- Ch 33: Wave Optics32
- Ch 34: Ray Optics57
- Ch 35: Optical Instruments30
- Ch 36: Special Relativity38
- Ch 37: The Foundations of Modern Physics25
- Ch 38: Quantization49
- Ch 39: Wave Functions and Uncertainty31
- Ch 40: One-Dimensional Quantum Mechanics35
- Ch 41: Atomic Physics18
- Ch 42: Nuclear Physics27
Knight Calc5th EditionPhysics for Scientists and EngineersISBN: 9780137344796Not the one you use?Change textbook
Chapter 5, Problem 52
Problems 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, and 52 describe a situation. For each, draw a motion diagram, a force-identification diagram, and a free-body diagram. A model rocket is fired straight down from the top of a tower.
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Identify the forces acting on the rocket: The rocket is subject to two primary forces. First, the gravitational force (weight) acts downward due to Earth's gravity. Second, there may be a thrust force from the rocket's engine, which also acts downward since the rocket is fired straight down.
Draw a motion diagram: Represent the rocket's motion with a series of dots indicating its position at successive time intervals. Since the rocket is accelerating downward (due to both gravity and thrust), the spacing between the dots should increase as time progresses.
Create a force-identification diagram: List all the forces acting on the rocket. These include the gravitational force (labeled as \( F_g \)) and the thrust force (labeled as \( F_{thrust} \)). Ensure you clearly identify the direction of each force.
Draw a free-body diagram: Represent the rocket as a single point. Draw vectors to represent the forces acting on it. The gravitational force vector \( F_g \) points downward, and the thrust force vector \( F_{thrust} \) also points downward. The length of each vector should be proportional to the magnitude of the respective force.
Analyze the net force: Since both forces act in the same direction (downward), the net force \( F_{net} \) is the sum of the magnitudes of \( F_g \) and \( F_{thrust} \). This net force causes the rocket to accelerate downward, as described by Newton's second law: \( F_{net} = m \cdot a \), where \( m \) is the mass of the rocket and \( a \) is its acceleration.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Motion Diagrams
A motion diagram visually represents the position of an object at various time intervals, illustrating its trajectory and speed. In the context of the model rocket, it will show the rocket's downward motion from the tower, indicating changes in position over time. This helps in understanding the kinematics involved in the rocket's descent.
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Work and PV Diagrams
Force Identification Diagrams
Force identification diagrams depict all the forces acting on an object at a given moment. For the model rocket, this includes gravitational force pulling it downward and any other forces, such as air resistance. Understanding these forces is crucial for analyzing the rocket's motion and predicting its behavior during descent.
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Free-Body Diagrams
Free-body diagrams are simplified representations that isolate an object and illustrate all the forces acting on it. In the case of the model rocket, the diagram will show the weight of the rocket acting downward and any opposing forces. This tool is essential for applying Newton's laws of motion to solve problems related to the rocket's acceleration and overall dynamics.
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Related Practice
Textbook Question
A rubber ball bounces. We'd like to understand how the ball bounces. A rubber ball has been dropped and is bouncing off the floor. Draw a motion diagram of the ball during the brief time interval that it is in contact with the floor. Show 4 or 5 frames as the ball compresses, then another 4 or 5 frames as it expands. What is the direction of a during each of these parts of the motion?
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Textbook Question
If a car stops suddenly, you feel 'thrown forward.' We'd like to understand what happens to the passengers as a car stops. Imagine yourself sitting on a very slippery bench inside a car. This bench has no friction, no seat back, and there's nothing for you to hold onto. Draw your free-body diagram. Is there a net force on you? If so, in which direction?
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Textbook Question
Problems 35, 36, 37, 38, 39, and 40 show a free-body diagram. For each: Identify the direction of the acceleration vector a and show it as a vector next to your diagram. Or, if appropriate, write a = 0.
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Textbook Question
Problems 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, and 52 describe a situation. For each, draw a motion diagram, a force-identification diagram, and a free-body diagram. A rocket is being launched straight up. Air resistance is not negligible.
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Textbook Question
Problems 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, and 52 describe a situation. For each, draw a motion diagram, a force-identification diagram, and a free-body diagram. A Styrofoam ball has just been shot straight up. Air resistance is not negligible.
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