1. Forces

2. * Force * A force is any push or pull on an object * Forces are measured in Newtons (N) * Forces are vectored quantities that shows both magnitude and direction.

3. * When forces are parallel, they can be combined by either addition or subtraction, to obtain the net force

4. * When forces are perpendicular (right angle) to each other, we use the Pythagorean Theorem (a 2 + b 2 = c 2 ) to find “c” the hypotenuse of a right triangle, to find the net force

5. * A few rules regarding perpendicular forces: * Always re-draw your force vectors so that the head of one vector is touching the tail of the other one * Draw your net force vector from the tail of the 1 st vector to the head of the 2 nd vector

7. * When forces are not parallel or perpendicular, they can be combined by using trigonometric functions of angles (math skills we haven’t learned yet) to find the net force.

8. * Types of Forces * Mechanical – when you use any part of your body or an extension of your body (bat, racket, stick, hammer, etc.) to apply a force

9. * Types of Forces * Electrical – the movement of electrons to cause something to happen (motor turning, lights shining, wires to heat up, etc.)

10. * Types of Forces * Chemical – the force that holds compounds together or are released in a chemical reaction

11. * Types of Forces * Nuclear – the forces that holds atoms together or that are released in a nuclear explosion

12. * Types of Forces * Gravitational – a force of attraction between any 2 objects

13. * Types of Forces * Friction – a force that opposes motion

14. * Types of Forces * Elastic – the rebound force found in rubber bands, springs and bouncing balls.

15. * In the late 1600s Sir Isaac Newton developed the 3 Laws of Motion.

16. * Newton’s 1 st Law of Motion states that a body at rest will stay at rest and a body in motion will stay in motion unless acted upon by an unbalanced outside force.

17. * According to Newton’s 2 nd Law of Motion, the formula for force is mass times acceleration * F = m(Kg)* a(m/s/s) * From the formula, the units for force is * Kg*m/s/s * This is called a Newton (N)

18. * Newton’s 3 rd Law of Motion is known as the “action-reaction” law because it states that for every action there is an equal and opposite reaction. * This explains why when riding on a skateboard when you push backwards on the ground you are propelled forward or * Why in a rocket the gases push downward to cause the rocket to go up.