ENERGY

What is energy? Energy is the capacity to do work or to produce heat.

Forms of Energy Energy comes in many forms, but they can be conveniently classified into three categories. Radiant Energy Kinetic Energy Potential Energy

What is radiant energy? Radiant energy is energy given off by the sun that can travel through empty space.

Examples of Radiant Energy Visible light X-rays Radio waves

What is kinetic energy (KE)? Kinetic energy is energy in motion.

Types of kinetic energy Mechanical energy EXAMPLE: a moving car Thermal (or heat) energy EXAMPLE: boiling a pot of water

What is potential energy (PE)? Potential energy is stored energy.

Types of potential energy Gravitational potential energy EXAMPLE: Electrical energy EXAMPLE:

Types of potential energy Chemical energy EXAMPLE:

Law of Conservation of Energy The law of conservation of energy states that energy is neither created nor destroyed. It can be transformed from one kind of energy into another.

Energy Transformation Modern civilization is possible because we have learned how to change energy from one form to another and use it to do work for us and to live more comfortably.

SOURCES OF ENERGY

Measuring Energy Energy can be measured using: a.) Calorie (C)  the energy stored in food b.) calorie (cal)  the amount of heat needed to raise the temperature of 1g of water x 1°C c.) Joule (J)  SI unit of energy (1 cal = J)

Practice Problems Conversion between calories and joules ( 1 cal = J) 1.If a container of water absorbs 25 calories of energy, how many joules of energy did the water absorb? (cal  J) (1 cal = J)

2.If a container of water absorbs 400 joules of energy, how many calories of heat did the water absorb? (J  cal) (1 cal = J)

3.Suppose you use 135 cal of energy to perform a task. How many joules have you used? (cal  J) (1 cal = J)

Practice Problems c. 20 kilocalories  joules 20,000 cal d. 2.4 kilojoules  calories 2,400 J

DO NOW: Energy Concept Map ENERGY

Energy Transformations Burning gas to drive a car chemical thermal mechanical

2.1 Review and Reinforcement Calorie and Joule Conversions 14. Convert 5.42 calories and joules. (1 cal = J)

15. Convert calories to kilojoules. (1 cal = J)

16. Convert 60.5 J to calories. (1 cal = J)