Energy, Work, and Momentum
Energy and Momentum
Work and energy
Work is energy transferred by a force through a distance. A simple form is when force and motion are in the same direction.
Kinetic and potential energy
Kinetic energy is energy of motion: . Potential energy is stored energy due to position or configuration.
Momentum
Momentum is defined as . It is a very important quantity because it is conserved in isolated systems.
Conservation
In a closed system, total energy and total momentum are conserved, meaning they do not change over time.
What is the formula for kinetic energy?
Kinetic energy depends on mass and the square of speed.
Correct answer:
What is momentum?
Momentum combines how much matter there is and how fast it is moving.
Correct answer: Momentum is mass times velocity, p = mv.
A simple conservation workflow
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1
Identify the system.
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2
Check whether external forces or energy transfers matter.
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3
Write the initial total quantity.
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4
Write the final total quantity.
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5
Set them equal if the system is isolated.
Which quantity is directly conserved in an isolated system?
Total momentum is conserved when no external force acts on the system.
Correct answer: Total momentum