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# Energy in motion

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### Energy in motion

1. 1. Energy in Motion<br />8SCIENCE Mon. May 16<br />
2. 2. How is energy related to motion?<br />Energy of matter in motion is called kinetic energy<br />Energy is the ability to cause a change or do work<br />Energy can be transferred between objects<br />Ex.: energy can be transferred through the momentum of objects (chest bounce)<br />Ex: chemical energy in a person gives muscles energy to kick a ball; energy is transferred from the leg and foot to the ball and the ball accelerates and gains the kinetic energy <br />
3. 3. Law of Conservation of Energy<br />Ex: as you kick a soccer ball, the energy from your leg is the same amount of energy transferred to the ball<br />This is the law of conservation of energy:<br />Energy is neither created or destroyed, but can only transform from one form to another<br />
4. 4. Calculating kinetic energy<br />Kinetic energy is the energy an object has because of its motion<br />Depends on mass and velocity<br />Kinetic energy = ½ (mass) (velocity)²<br /> KE = ½ mv²<br />Unit of energy is called the joule (J), named for James Joule, a scientist<br />(1 joule = 1 kg x m²/s²)<br />
5. 5. Potential Energy<br />Potential energy is the stored energy of a position<br />Ex: a book about to fall off a table has potential energy – if you knock it off, it will accelerate towards the ground because of gravity<br />Gravitational potential energy (GPE) is the energy an object could change to kinetic energy if it falls<br />Depends on the mass (m) and height (h)<br />GPE = (mass) (force of gravity) (height)<br />GPE = mgh<br />
6. 6. How are GPE and KE related?<br />Ex: Throwing a ball into the air<br />When you first throw a ball into the air, ithas kinetic energy (KE) because it is moving<br />As it reaches a point in the air and stops moving, this kinetic energy changes to potential energy<br />This potential energy changes to kinetic energy as the ball falls back towards the ground<br />Ex: Imagine you are riding a slide<br />At the top, you have potential energy, before you let yourself move down the slide<br />As you fall, this changes to kinetic energy because you are moving<br />