The connection between energy and work is very important in physics. It also plays a big role in our everyday lives.

1. Definitions:

   • Energy: This is the ability to do work. It's measured in something called joules (J).
   • Work: This happens when energy moves from one place to another. It takes place when a force is used over a distance. You can think of it like this:
     • Work (W) = Force (F) × Distance (d) × Cosine of the angle (θ) between the force and the direction of movement.

2. Everyday Applications:

   • Transportation: Cars use fuel to create movement. They change chemical energy into kinetic (moving) energy. Usually, they only use about 15% to 30% of this energy efficiently.
   • Electricity: Our home devices use electrical energy to do work. On average, a household in the U.S. uses about 877 kilowatt-hours (kWh) of electricity every month.
   • Exercise: When we work out, we turn the chemical energy from our food into movement. For example, running one mile needs about 100 calories, which is about 418.4 kilojoules of energy.

3. Conservation of Energy: There's a rule called the law of conservation of energy. It tells us that in a closed system, the total amount of energy stays the same. This means energy can change from one form to another, but it can't be created or destroyed.