# Work and Energy - Physics 101 / AP Physics 1 Review with Dianna Cowern | Summary and Q&A

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November 12, 2020
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Physics Girl
Work and Energy - Physics 101 / AP Physics 1 Review with Dianna Cowern

## TL;DR

This lesson introduces the concepts of energy and work in physics, explaining how work is defined as force multiplied by distance and how energy is the transfer of work or heat. It also covers kinetic energy, potential energy, conservative and non-conservative forces, and the relationship between energy and gravity.

## Key Insights

• 💦 Energy and work are fundamental concepts in physics, defining the transfer and quantification of energy in various forms.
• 🥺 Work is defined as the product of force and distance and can lead to changes in an object's energy state.
• 🧘 Energy can be classified as kinetic energy (related to an object's motion) and potential energy (related to an object's position).
• 💦 The units for work and energy are joules (J), named after James Prescott Joule, an English brewer and scientist who conducted experiments to understand the relationships between heat, energy, and work.
• 💁 Gravity is a conservative force, meaning it does not do work or transfer energy on objects moving along circular orbits. Friction, on the other hand, is a non-conservative force that converts mechanical energy into heat or other forms of energy dissipation.

## Transcript

HOST: This is a bowling ball attached to a rope. And I'm going to hold it up to my face and let it swing away and swing back. And I'm just going to stay here. Watch what happens. Oh my gosh. Oh my gosh. Aah! [LAUGHING] Hello, and welcome to lesson 9 of Dianna's Intro to Physics Class, also known as AP Physics 1 Review, also known as Physics by Dian... Read More

### Q: What is the definition of work in physics?

In physics, work is defined as the product of force and distance, or the force exerted on an object over a specific distance or change in position. It is a measure of the change in energy experienced by an object due to the application of a force.

### Q: What is the relationship between work and energy?

Work and energy are closely related concepts in physics. Work is the transfer of energy to or from an object, resulting in a change in energy state. When work is done on an object, it gains energy, and when work is done by an object, it loses energy. In other words, work is the process of transferring energy from one form to another.

### Q: How is kinetic energy defined, and what factors affect it?

Kinetic energy is the energy of an object due to its motion. It is directly proportional to the mass of the object and the square of its velocity. So, an object with a higher mass or higher velocity will have more kinetic energy. The formula for kinetic energy is KE = 1/2 * mass * velocity^2.

### Q: What is the difference between conservative and non-conservative forces?

Conservative forces are those that can store and transfer potential energy. Examples include gravity and spring forces. Non-conservative forces, on the other hand, do not store potential energy and typically result in energy losses, such as friction. Non-conservative forces convert mechanical energy into heat or other forms of energy dissipation.

## Summary & Key Takeaways

• The video explains the concepts of energy and work in physics, focusing on the transfer of work and the quantification of heat and work done on an object.

• It discusses the definitions of force, distance, work, and energy, and how they are all interconnected.

• The video demonstrates the calculation of work and energy by solving several problems, such as determining the work done by a rocket and finding the velocity of an object using kinetic energy.