1. Force

2. a push or a pull a force gives energy to an object causing it to… –start moving, stop moving, or change direction the unit of measurement is Newtons (N) –used to be a kg(m/s 2 ) –this is about ¼ pound forces in the same direction are added to make the resulting force stronger forces in different directions are subtracted which makes the resulting force weaker –if these forces are equal, they are balanced forces

4. Types of Forces Contact Forces: the objects involved are touching each other and friction is created –friction is a force that is in the opposite direction to the moving object and therefore, slows it down –3 types of friction rolling sliding fluid – this is caused by an object moving through a liquid or a gas

5. Non-contact forces: objects are pushed or pulled without being touched –gravity –electricity –magnetism

6. F = Force m = mass a = acceleration F = ma or F = m·a or F = m x a or F = m(a) Force formula

7. Two ways an object has force and how to use the force formula 1.Object is accelerating. –if it is rolling, flying, and/or sliding it has a force –think of a car hitting you 2.Object is NOT moving (more on this later) –this is a result of gravity –think of a car on top of you!

8. Example problem A rocket has a mass of 3.5 kg and an acceleration of 3.0 m/s 2. What is the rocket’s force? m=3.5kg F=ma a=3.0m/s 2 given formula set up problem answer w/ unit of measurement A kg(m/s 2 ) is the same as a Newton so 10.5 N would be the same, but simpler. 3.5kg(3.0m/s 2 )10.5 kg(m/s 2 )