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Ch 09: Work and Kinetic Energy
Knight Calc - Physics for Scientists and Engineers 5th Edition
Knight Calc5th EditionPhysics for Scientists and EngineersISBN: 9780137344796Non è quello che usi tu?Cambia libro di testo
Capitolo 9, Problema 32

A 55 kg softball player slides into second base, generating 950 J of thermal energy in her legs and the ground. How fast was she running?

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1
Identify the type of energy conversion taking place: The kinetic energy of the softball player is being converted into thermal energy due to friction. The thermal energy generated is given as 950 J.
Write the formula for kinetic energy: \( KE = \frac{1}{2} m v^2 \), where \( m \) is the mass of the player (55 kg) and \( v \) is her velocity (to be determined).
Set the kinetic energy equal to the thermal energy generated: \( \frac{1}{2} m v^2 = 950 \).
Rearrange the equation to solve for \( v \): \( v = \sqrt{\frac{2 \cdot 950}{m}} \).
Substitute the given mass \( m = 55 \ \text{kg} \) into the equation: \( v = \sqrt{\frac{2 \cdot 950}{55}} \). Simplify the expression to find the velocity.

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Kinetic Energy

Kinetic energy is the energy an object possesses due to its motion, calculated using the formula KE = 1/2 mv², where m is mass and v is velocity. In this scenario, the kinetic energy of the softball player can be equated to the thermal energy generated during the slide, allowing us to solve for her running speed.
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Intro to Rotational Kinetic Energy

Conservation of Energy

The principle of conservation of energy states that energy cannot be created or destroyed, only transformed from one form to another. In this case, the kinetic energy of the player is converted into thermal energy as she slides, which is crucial for understanding how to relate her speed to the energy generated.
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Conservation Of Mechanical Energy

Work-Energy Principle

The work-energy principle asserts that the work done on an object is equal to the change in its kinetic energy. When the player slides into second base, the work done by friction between her legs and the ground results in the generation of thermal energy, which can be quantified to find her initial speed before the slide.
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The Work-Energy Theorem
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