1. Newton’s 1 st Law of Motion – The Law of Inertia 12/5/14

2. F.B.D. and 3 rd Law Homework

3. Newton’s 1 st Law of Motion (re-cap)  Lex I: Corpus omne perseverare in statu suo quiescendi vel movendi uniformiter in directum, nisi quatenus a viribus impressis cogitur statum illum mutare.  Law I: Every body persists in its state of being at rest or of moving uniformly straight forward, except insofar as it is compelled to change its state by force impressed.  An object at rest stays at rest and an object in motion stays in motion with the same velocity unless acted upon by an unbalanced force.

4. Forces may be balanced or unbalanced  Balanced forces – the sum of all forces acting on an object are equal to zero  There is no acceleration but can have constant velocity  Unbalanced forces – the sum of all forces acting on an object are NOT equal to zero, there is a net force  There is acceleration so the velocity will be changing  Objects do not change their motion unless a force acts on them

5. Balanced Force Equal forces in opposite directions: a) can be at rest b) has a constant velocity

6. Unbalanced Forces Unequal opposing forces produce an unbalanced force Causing an acceleration (increase of velocity)

7. Unbalanced Forces a)If the truck starts at rest or is moving to the right then it will accelerate to the right

8. Unbalanced Forces b) If the truck starts at is moving to the left then it will accelerate to the right (decease of velocity)

9. Inertia  Mass (scalar): is the amount of matter in an object. Unit is kilograms (kg).  Inertia (scalar): the tendency of a body to resist change to its motion (acceleration).  The more MASS an object has, the more INERTIA the object has.  Bigger objects are harder to start & stop

10. If objects in motion tend to stay in motion, why don’t moving objects keep moving forever? Things don’t keep moving forever because there’s almost always an unbalanced force acting upon them. A book sliding across a table slows down and stops because of the force of friction. If you throw a ball upwards it will eventually slow down and fall because of the force of gravity.

11. Newton Story / Comic Board are due on Tues. 12/9/14