energy. what is energy? energy is the capacity to do work or to produce heat
TRANSCRIPT
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 beconveniently classified into three categories.
Radiant Energy
Kinetic Energy
Potential Energy
What is radiant energy?
Radiant energy is energy given off by thesun 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 energyEXAMPLE: a moving car
Thermal (or heat) energyEXAMPLE: boiling a pot of water
What is potential energy (PE)?
Potential energy is stored energy.
Types of potential energy
Gravitational potential energyEXAMPLE:
Electrical energyEXAMPLE:
Types of potential energy
Chemical energyEXAMPLE:
Law of Conservation of Energy
The law of conservation of energy states that energy is
neither created nor destroyed. It can betransformed from one kind of energy into
another.
Energy Transformation
Modern civilization is possiblebecause we have learned how tochange energy from one form toanother and use it to do work forus 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 ReinforcementCalorie 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)