Newton’s Laws of Motion

1. Newton’s Laws of Motion

2. First Law of Motion • An object in motion tends to stay in motion, an object at rest tends to stay at rest. Unless, acted upon by an unbalanced force. • Examples -

3. 1stLofM • Scientists used to believe that constant motion required a constant supply of force. • THIS WAS WRONG!

4. 1stLofM • Inertia – The property of an object that resists changes in its motion. • 1stLofM often called the law of inertia. • Changes in motion come from unbalanced forces. • What is a balanced for called?

5. 1stLofM • Net forces affect motion. • Remember to include positive and negative signs when combining forces.

6. Second Law of Motion • Illustrates the connection between force, mass, and motion. • The Newton (unit of force) is defined by the second law. • In the presence of a net force an object experiences an acceleration. • Summed up by F=ma

7. 2ndLofM • Three main ideas related to the 2ndLofM • Acceleration is the result of unbalanced forces. • A larger force makes a proportionally larger acceleration. • Acceleration in inversely proportional to mass.

8. 2ndLofM • Rearrange the force formula to solve for each of the 3 variables.

9. 2ndLofM • The net force is what causes acceleration • If there is not acceleration, the net force must be zero. • If there is acceleration, there must also be a net force. • The force unit of newtons is based on kilograms, meters, and seconds. Therefore, when solving you must convert your units to kg, m, and s

10. 3rd Law of Motion • For every action there is an equal and opposite reaction. • Forces always come in pairs (action/reaction)

11. 3rdLofM • Aides in sorting out action/reaction pairs • Both are always there whenever any force appears. • They always have the exact same strength. • They always act in opposite directions. • They always act on different objects • Both are real forces and can cause changes in motion.