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
Potential vs. Kinetic Energy What is the relationship between potential and kinetic energy? Is it possible to have both potential and kinetic energy?
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
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.
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
Speed practice problems 1. If a car travels 400m in 20 seconds how fast is it going?
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?
Speed practice problems 3. How far will your little brother run if he can travel at 2.5 m/s for 50 seconds?
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?
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?
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!
Speed graphs Average speed can be calculated from a graph by dividing the total distance by the total time. S = D/t
Speed graphs Graphs can tell a story about the motion of an object