1. Motion http://commons.wikimedia.org/wiki/File:Soccer_kick.jpg

2. Key Understandings
Changes in motion can be measured and graphically represented.
Forces cause changes in position, speed, and direction.

3. What is motion anyway?
Motion is a change in position, which is measured by distance and time.
Anything moving is in motion.

4. What changes motion? A force is a push or pull that can change motion.
A force can move an object.
A force can transfer energy to an object.
For example, pushing on a wall doesn’t move the wall, but energy is being transferred.

5. Unbalanced Forces
In order for a force to move an object, there must be unbalanced forces.
Like tug of war…the winners are pulling the other team with more force; therefore, the pulling forces are unbalanced.

6. How can unbalanced forces affect objects?
Unbalanced forces can change the position, speed, or direction of an object.
Resistance forces (friction or wind) that oppose motion can slow down an object.
A force in the same direction can cause an object to speed up.
A force from a different direction can change the object’s direction.

7. Balanced Forces
If we have unbalanced forces, then there must be balanced forces.
When forces are balanced, an object’s motion will be constant. It will not change speed or direction.

8. Speed We talk about speed everyday.
Speed is the distance traveled by a moving object per unit of time.
Speed affects the energy of an object. The faster it moves, the more kinetic energy it has.
Speed = distance
time

9. Calculating Speed
If I traveled 30 meters in 10 seconds, what was my speed?
S = D/T
30m/10s
3 m/s

10. Kinetic Energy The energy of motion
Objects in motion have kinetic energy.

11. Distance
Distance is a description of how far an object traveled between two points.

12. Velocity
Velocity and speed are like fraternal twins- very similar, but with important differences.
Velocity is speed in a given direction.
35 mph NORTH
4 km/sec EAST

13. Which is which? 100 m/s right 1500 km/s 65 m/s north 3000 km/s
Velocity
Speed

14. Acceleration Acceleration is the change in velocity.
It can be a change in speed, direction, or both.

15. Friction Friction is a force that opposes motion.
It can be caused by wind, water, surface texture, etc.
Have you ever ridden down the street on your bike and felt the wind push against you?
That’s air resistance!