Transcript ENERGY - WOHS Portal

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 = 4.184 J)
Practice Problems
Conversion between calories and joules ( 1 cal = 4.184 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 = 4.184 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 = 4.184 J)
3.Suppose you use 135 cal of energy to perform a task. How
many joules have you used? (cal  J)
(1 cal = 4.184 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 = 4.184 J)
15. Convert 726.030 calories to kilojoules.
(1 cal = 4.184 J)
16. Convert 60.5 J to calories. (1 cal = 4.184 J)