1. Potential vs. Kinetic Energy
Potential Energy – Stored energy
-Gravitational - related to height, caused by gravity
Examples: Lifting an object, going up a hill, throwing a ball into the air.
-Elastic related to stretch or compression
Examples : Stretching a rubberband, squishing a spring
Kinetic Energy – Energy of motion (speed)
-The more kinetic energy an object has, the faster it moves.
Examples: A rubber band flying through the air, a ball falling

2. Potential vs. Kinetic Energy
What is the relationship between potential and kinetic energy?
Is it possible to have both potential and kinetic energy?

3. Balanced and unbalanced forces
Balanced Forces – Net force is 0. The object’s motion will not change
-Objects in motion stay in motion (same speed and direction), objects at rest will stay at rest (kind of like Inertia).
-Acceleration = 0
Unbalanced Forces – Net force is >0. The object will accelerate.
Accelerate – Any change in the speed or direction of an object’s motion
1. Speed up
2. Slow down
3. Change direction
You can calculate the acceleration of the object with F=ma

4. Balanced and unbalanced forces
How do I find out of the forces are balanced or unbalanced?
If the object is accelerating, the forces are unbalanced. If the object’s motion is not changing, the forces are balanced.
Using a diagram, calculate the net force.

5. speed -Speed is the distance is object travels per unit of time.
-It can be calculated with the equation
Speed = Distance / Time OR
S = D/t

6. Speed practice problems
1. If a car travels 400m in 20 seconds how fast is it going?

7. Speed practice problems
2. How much time will it take for a bug to travel 5 meters across the floor if it is traveling at 1 m/s?

8. Speed practice problems
3. How far will your little brother run if he can travel at 2.5 m/s for 50 seconds?

9. Speed graphs
Motion can be represented on a graph. Different types of motion will have
different types of graphs to represent them.
The slope of the line represents the speed of the object.
Which line above demonstrates the fastest motion? Slowest? How can you tell?

10. Speed graphs
Motion can be represented on a graph. Different types of motion will have
different types of graphs to represent them.
More slope = more speed
Less slope = less speed
No slope = ??
What does this graph show?

11. Speed graphs
Motion can be represented on a graph. Different types of motion will have
different types of graphs to represent them.
What does this graph show?
Each change in the slope of the graph is acceleration, caused by unbalanced forces!

12. Speed graphs
Average speed can be calculated from a graph by dividing the total distance by the total time.
S = D/t

13. Speed graphs
Graphs can tell a story about the motion of an object