Cheri Scheer Energy

Energy Science 7 th grade Stand 1 Objective 2 GLE

OVERVIEW

Kinetic energy Energy an object has due to motion Examples –rock rolling down the hill –bike moving along the road Increasing mass and speed also increases an object’s kinetic energy

Potential energy Energy that is stored Example –Ball at top of hill –Leaf hanging from limb Changing an object’s position to some place higher, increases the object’s potential energy

Kinetic and Potential Energy

Energy The ability to cause changeThe ability to cause change FormsForms  Mechanical  Chemical  Electrical  Thermal or heat  Radiant  Sound  Nuclear website

Mechanical energy Potential- stored energy –examples: Kinetic-energy of a moving object –Examples: –Energy in machines

Chemical Energy Energy trapped in chemical bonds (Stored in foods or fuels) Chemical reactions happen when compounds are broken down or created.

Types of chemical reactions Endothermic- absorbs heat: food as it cooks, baking soda giving off gas as it heats causing cookies to rise. Exothermic-give off heat: substance burns turning into heat Both happen continuously in your body Catalyst- is a substance that changes the rate of the reaction

Electrical energy Energy associated with magnet, electrical circuits and combinations of the two Examples:

Heat Energy Energy given off by a hot object Also called thermal energy Different materials act as insulators or conductors of heat Examples:

Nuclear Energy Energy locked in the nucleus of the atom Examples:

Light energy Energy carried in a beam of light Also known as radiative energy examples

Conservation of Energy Energy CAN NOT be created or destroyed. Energy is changed to another form.

Temperature All objects have molecules that are in motion. Therefore, all objects have kinetic energy. Increasing temperature also increases kinetic energy.

Heat A transfer of energy from one object to another due to a difference in temperature. Heat flows from warmer objects to cooler ones until both objects are equal in temperature. The amount and type of material effects how temperature will change.

Transfer of Heat Conduction – mainly through solids and liquids Convection – mainly through liquids and gases Radiation – transfers energy through space

Conduction The transfer of energy by collisions between the atoms and molecules in a material. Conductors are materials through which energy is easily transferred. –All metals (gold, silver, copper) –Copper is less expensive and more readily available

Insulators Poor conductors of heat Examples –Cloth(blankets and clothes) –Air –Plastic –Wood –Rubber –Tile

Convection Transferring heat when particles move between objects or areas that differ in temperature Thermals are columns of warm air that is forced up as cooler air sinks. –Aids birds to fly without moving wings

Radiation Transferring energy by waves Can be visible or invisible waves Example –Sun heats Earth –Warming self by fire –Microwave cooking

Chemical Energy Energy trapped in chemical bonds (Stored in foods or fuels) Chemical reactions happen when compounds are broken down or created.

Chemical Reactions To break a bond, energy must be added. To form a bond, energy is released. H20H20

Types of chemical reactions Endothermic- absorbs heat: food as it cooks, cookies rising when baking, photosynthesis Exothermic-give off heat: substance burns turning into heat Both happen continuously in your body Catalyst- is a substance that changes the rate (speed) of the reaction

REVIEW

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