POTENTIAL AND KINETIC ENERGY

What we already know! No object can move unless a force is applied to it. This is pretty much summarized in Newton’s First Law of Motion, also known as the LAW OF INERTIA

Energy cannot be created or destroyed, but it can be changed from one form to another. (Law of Conservation of Energy) Energy is required to move an object. Energy can be classified into 2 categories. Those 2 categories are Kinetic energy ( Energy of Motion) and Potential energy, (Some type of stored energy) Kinetic-> Motion Potential->Stored

Kinetic Energy Kinetic energy is basically the energy of Motion. That is to say, the faster an object is moving, the more kinetic energy it displays. Example: A person running would display more kinetic energy than a person walking, all other things being equal. If an object accelerates, then it is increasing it’s kinetic energy.

Potential Energy Potential energy can be explained as some type of stored energy. That could be lots of different things. Potential energy can be stored in a battery, A skateboarder on top of a hill has gravitational potential energy because they could roll down the hill. Of course, when they do start rolling down the hill, their potential energy is converted into kinetic energy, because their speed increases.

On a roller coaster Top of rise, maximum potential energy, but not so much kinetic energy Bottom of hill, maximum KE (speed) but not so much PE.

Potential to Kinetic/Kinetic to Potential A bow pulled back to launch an arrow would demonstrate Potential energy. When the arrow is launched, the potential energy is converted into kinetic energy. A swing is a great example of potential energy being converted into kinetic energy and back again.

KINETIC ENERGY AND TEMPERATURE When matter, such as water is heated and the molecules absorb Kinetic Energy (KE) from the heat source and move faster. As they move faster, their temperature rises, and we say the material is heating up. Measuring with a thermometer will show that the water has increased in temperature and thus has speeded up (increased it’s kinetic energy level)

Speed Speed is rate quantity. Specifically: speed is a measurement of distance covered over time. Formula for speed is Speed =Distance/time S=D/T Units for speed examples: Miles per hour (mi/hr) Meters per second (m/sec), many other examples

Reminders about speed An object going a constant speed is experiencing balanced forces Unbalanced forces can cause – positive acceleration (increasing speed) or – negative acceleration (decreasing speed: AKA deceleration) – Or a change in direction A change in acceleration can happen in 2 ways: 1. Change in speed 2. Change in direction Both of these require a force

What is the speed of the cyclist from 2-4 hours? What is the speed of the roller coaster from 1 seconds to 5 seconds? Which graph shows a constant speed? What is the average speed of the roller coaster? What happens to the roller coaster between 2 and 3 seconds? It is obvious that the 2 graphs are different. List as many ways as possible how they are differnent?