Domanda del libro di testo
A tennis racket swung over the server's head hits a tennis ball horizontally. Draw a free-body diagram for each object in the system. Use dashed lines to connect members of an action/reaction pair.
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Ch 07: Newton's Third Law
Knight Calc5th EditionPhysics for Scientists and EngineersISBN: 9780137344796
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TOC.tableOfContents
- 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: 9780137344796Non è quello che usi tu?Cambia libro di testo
Capitolo 7, Problema 2b
A weightlifter stands up at constant speed from a squatting position while holding a heavy barbell across his shoulders. Identify the "system" on your interaction diagram.
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Define the system: The system includes the weightlifter (his body) and the barbell he is holding. This is because we are analyzing the forces acting on both the weightlifter and the barbell as a combined system.
Identify external forces: The external forces acting on the system are the gravitational force (weight) acting downward on both the weightlifter and the barbell, and the normal force exerted by the ground upward on the weightlifter's feet.
Clarify internal forces: Internal forces include the forces within the weightlifter's body, such as the muscular forces exerted by his legs to lift his body and the barbell. These forces are internal to the system and do not affect the net external force.
State the motion condition: Since the weightlifter is moving at a constant speed, the system is in dynamic equilibrium. This means the net external force acting on the system is zero, as there is no acceleration.
Summarize the interaction diagram: The interaction diagram should show the system (weightlifter + barbell) with arrows representing the external forces: the downward gravitational force and the upward normal force. Internal forces are not shown in the interaction diagram as they cancel out within the system.
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System Definition
In physics, a 'system' refers to a specific portion of the universe chosen for analysis, which can include objects, forces, and interactions. In this context, the system encompasses the weightlifter and the barbell, as they are the primary subjects of interest in understanding the forces and motions involved.
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Percorso guidato
06:48
Systems Of Objects with Energy Conservation
Free Body Diagram
A free body diagram is a graphical representation used to visualize the forces acting on an object. For the weightlifter, this diagram would illustrate the gravitational force acting downward on the barbell and the weightlifter, as well as the normal force exerted by the ground, which balances these forces when the lifter moves at constant speed.
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Percorso guidato
08:42Free-Body Diagrams
Newton's Second Law
Newton's Second Law states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. In this scenario, since the weightlifter is moving at constant speed, the net force is zero, indicating that the upward force exerted by the lifter equals the downward gravitational force acting on the barbell and his body.
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Percorso guidato
06:54Intro to Forces & Newton's Second Law
Pratica correlata
Domanda del libro di testo
Block A in FIGURE EX7.4 is sliding down the incline. The rope is massless, and the massless pulley turns on frictionless bearings, but the surface is not frictionless. The rope and the pulley are among the interacting objects, but you'll have to decide if they're part of the system. Draw an interaction diagram.
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Domanda del libro di testo
Block A in FIGURE EX7.4 is sliding down the incline. The rope is massless, and the massless pulley turns on frictionless bearings, but the surface is not frictionless. The rope and the pulley are among the interacting objects, but you'll have to decide if they're part of the system. Draw a free-body diagram for each object in the system. Use dashed lines to connect members of an action/reaction pair.
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Domanda del libro di testo
A heavy steel cable attached to a motor is lifting a girder. The girder is speeding up. Draw an interaction diagram.
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