1. Forces

2.  > Identify the law that says that objects change their motion only when a net force is applied.  > Relate the first law of motion to important applications, such as seat belt safety issues.  > Calculate force, mass, and acceleration by using Newton’s second law.

3.  Sir Isaac Newton  British scientist (1642-1727)  Force  Gravity  Calculus http://www.youtube.com/watch?v=iH48Lc 7wq0U Newtons Law's Clip

4.  He formed 3 laws to show the relationship between motion and force.  Motion- change in position  Force- a push or pull that affects motion of an object

5.  An Object at rest remains at rest and an object in motion maintains its velocity unless acted upon by an unbalanced force.

6.  An unbalanced force must be greater than zero  Inertia (def)- the tendency of an object to resist change in its velocity or lack of

7. Inertia Clip Inertia Clip

8.  The ability of matter to resist a change in motion is dependent on its mass.  Larger masses are harder to change than smaller

9.  Example- playing softball with a bowling ball  Seatbelts provideprotection against a persons own inertia.

10.  The unbalanced force acting on an object equals the objects mass times its acceleration  Force= mass X acceleration F=m x a

11.  Mass- amount of matter in an object  Acceleration- any change in velocity ex.  Empty vs full cart.  Size of force and mass effect acceleration.

12.  SI units for force is NEWTON- a derived unit (2 units put together)  kg x m/s 2 mass (kg)and acceleration (m/s 2)  F= (m * a)  a= F/m