Potential and Kinetic Energy

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What is energy? When an object is able to change it’s environment, we say the object has energy. The use of energy involves change Forms - radiant, electrical, chemical, thermal and nuclear ENERGY = the ability to cause a change

How is all energy divided? Potential Energy Kinetic Energy All Energy

What is Potential Energy? oEnergy that is stored and waiting to be used later oExplain how this flower pot has potential energy.

What is Kinetic Energy? oEnergy in the form of motion oThe greater the mass of a moving object, the more K.E. oThe greater an objects velocity the more K.E.

WORK = The transfer of energy through motion. In order for work to take place, a force must be exerted through a distance.

Calculating Work When a force acts over a distance in the direction of an object’s motion, the work done can be calculated as work = Force x Distance W = F x d

Calculating Work Which would require more work? Lifting a pack of gum from the floor to waist level or lifting a pile of books through the same distance? The amount of work done depends on Amount of force exerted Distance over which force is applied

When is Work Being Done? Something has to be moving The motion must be in the same direction as the applied force.

Conservation of Energy Think about swinging on a swing. How does the energy during these movements change?

Mechanical Energy The total amount of kinetic and potential energy in a system

Law of Conservation of Energy Energy may change from one form to another, but the total amount of energy stays the same. The Law of Conservation of Energy states that energy may change form but it cannot be created or destroyed under ordinary conditions.

The Mechanical Energy is not Lost Will the swing go back and forth forever? Why? Where does the energy go?

The Human Body What forms of energy are in the human body? With your left hand, reach your right shoulder. We just converted ________________ energy in our bodies into ________________ energy in our arms.

Balancing Energy Within our Bodies In our bodies, stored energy (that found in fat) is lost when work is done or heat is lost by your surroundings. To maintain healthy weight, you must have proper balance between energy taken in and energy lost from your body as work or heat.

Food  Our Chemical Potential Energy Think about what you ate this morning. Your body has been chemically changing your food into molecules that can combine with oxygen and be used as fuel. Even if you didn’t eat breakfats, the stored fat in your body is converted to energy.

Measuring Food Energy CALORIE = 4,180 joules Every gram of fat a person consumes can supply 9 Calories of energy. Carbohydrates and proteins supply about 4 Calories of energy per gram.

Why do our bodies need an energy supply?