1. Forces and Motion…Forces and Motion…
Everyday pushes and pullsEveryday pushes and pulls
(that we never think about)(that we never think about)

2. Everyday ForcesEveryday Forces
Forces
Gravitation Magnetism Friction

3. Gravity:Gravity: the pull between all objects (thethe pull between all objects (the
greater the mass, the harder the pull!!!)greater the mass, the harder the pull!!!)
 Discovered by Sir Isaac NewtonDiscovered by Sir Isaac Newton
when an apple fell upon hiswhen an apple fell upon his
head…head…

4. Friction: causes motion to slow down or stop… causes drag!Friction: causes motion to slow down or stop… causes drag!
Friction keeps us
from sliding off
the skateboard.
The rough surface of the mountain
causes friction and gives us a grip
on the side of the mountain when
we rock climb.
The tread on our shoes causes
friction, and keeps us from ending
up like this guy on icy roads.

5. Balanced forces are equal in size and opposite inBalanced forces are equal in size and opposite in
direction.direction.
When forces are balanced, no change in motion occurs.

6. Unbalanced forces are NOT equal in size and
Unbalanced forces are NOT equal in size and
opposite in direction.
opposite in direction.
When forces are unbalanced, a change in motion occurs.

7. How can I tell when motion is occurring???How can I tell when motion is occurring???
I need to know an objectI need to know an object’s starting’s starting positionposition to beto be
able to tell it has moved over a distance!able to tell it has moved over a distance!
Distance

8. Speed: How long it takes to travel a givenSpeed: How long it takes to travel a given
distancedistance
 Formula: Distance/Time = SpeedFormula: Distance/Time = Speed
 Ex: 55 miles/1 hour = 55 miles per hourEx: 55 miles/1 hour = 55 miles per hour
Distance = 55 miles
Time = 1 hour

9. Graphing Speed:Graphing Speed:
Distance vs. Time GraphDistance vs. Time Graph
Phoenix
Denver

10. Question:Question:
Below is a distance vs. time graph for 3Below is a distance vs. time graph for 3
runners. Who is the fastest?runners. Who is the fastest?
Leroy is the fastest. He completed the race in 3 hours.

11. How fast something looks like itHow fast something looks like it’s moving all’s moving all
depends on yourdepends on your frame of referenceframe of reference ..

12. Velocity: The speed of an object in aVelocity: The speed of an object in a
particular direction.particular direction.
 Example:Example:
An airplane moving North at 500 mphAn airplane moving North at 500 mph
A missile moving towards you at 200 m/sA missile moving towards you at 200 m/s

13. Question:Question:
What is the difference between speed
and velocity?
Speed is just distance/time. Velocity includes
direction as well.

14. The rate at which velocity changes is calledThe rate at which velocity changes is called
accelerationacceleration..
It can be:
•an increase in speed
•a decrease in speed
•a change in direction

15. Question:Question:
How can a car be accelerating if its speed
is a constant 65 km/h?
If it is changing directions it is accelerating

16. Momentum: How hard it is to start or stop an object.Momentum: How hard it is to start or stop an object.
The more mass an objectThe more mass an object
has, the more momentumhas, the more momentum
it has.it has.
Ex:Ex: ItIt’s harder to stop a 200 lb.’s harder to stop a 200 lb.
linebacker than a 100 lb.linebacker than a 100 lb.
ballerinaballerina
The faster an object is moving, the more momentum it has.
Ex: It’s harder to stop a car going 50 miles an hour than a car going
10 miles an hour.