# 玩微信红包扫雷有猫腻

Science class online
Chemistry and physics lessons

# Mechanics

Free online mechanics lesson for elementary school,  middle school and high school.

 Science class Chemistry Electricity Optics Mechanics Mechanics lessons Gravity - The solar system - motions of celestial bodies - Physical interactions - Effects of gravity - Weight of an object - Difference between weight and mass - Relationship between weight and mass  Energy - Energy basics - Potential energy - Kinetic energy - Mechanical energy - Translational Kinetic Energy - kinetic energy mass and speed

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## Gravity

### Potential energy

 A ball that is dropped upon some sand creates a crater whose dimensions depend on the ball's energy at the time of impact: more energy for the ball will result a deeper and wider crater. We can notice the crater's size depends on two factors: - The size of the crater increases with height of fall - The size of the crater increases with the ball's mass ______________________________________ ______________________________________ Thus we can conclude that every object owns an energy that depends on its height and it mass. Such an energy is called " potential energy ". Potential energy is denoted by PE and can be expressed in Joule. An object's potential energy increases if its height or its mass increases.
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