| force | Any influence that tends to accelerate an object. |
| weight | The force on a body due to the gravitational attraction of another body. |
| interaction | A mutual action between objects where each object exerts an equal and opposite force on the other |
| newton's 3rd law | Whenever one body exerts a force on a second body, the second body exerts an equal and opposite force on the first. |
| action force | One pair of forces described in Newton's 3rd law. |
| reaction force | The force that is equal in strength and opposite in direction to the action force, which acts simultaneously on whatever is exerting the action force. |
| mass | The amount of matter in an object; a measure of an object's inertia. |
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