Download !!!Energy!!!

!!!Energy!!!
What is Energy?
Energy is the property of an object that
enables it to do work.
Energy is measured in joules ( j )
But what do we mean by “Work”?
What is Work?
Work is done when a force causes an object to
move over a certain distance in the direction of the
force .
20N
10m
Work is equal to the Force used to move the object multiplied by
the distance it caused the object to travel.
W =F x d
Work is also measured in joules ( j )
When work is done on an object, energy is transferred to that object
The work done when the box moved is 20N x 10m = 200j
Types of Energy
There are many different kinds of energy.
Chemical energy is a type of energy stored in chemical
bonds found in :
Batteries
Gasoline
Food
Types of Energy
Thermal energy is associated
with heat
Sound energy is energy associated with sound
(longitudinal mechanical) waves.
Types of Energy
Light energy is energy that associated
with light (electromagnetic) waves
Electrical energy is energy associated
with current and voltage.
Types of Energy
Nuclear Energy
The energy that is released during a nuclear reaction.
Splitting atoms (fission) and fusing atoms (fusion) both
release nuclear energy.
Nuclear power plants use fission to
produce energy, which allow them
to generate electricity on a large
scale
Types of Energy
Kinetic energy is energy of motion. It is the energy that all
moving objects have.
The amount of kinetic energy an object has depends on two factors:
Velocity (Speed) and Mass
1) Velocity (Speed): Kinetic energy is greater when the speed is greater
More Kinetic Energy
Less Kinetic Energy
Types of Energy
2) Mass: Kinetic energy is greater when the mass of the object is
greater
More Kinetic Energy
Less Kinetic Energy
Types of Energy
Potential energy is energy that is stored.
Example: Gravitational potential energy ie energy that is stored due to
the position of an object.
The amount of Gravitational potential energy an object has depends
on two factors:
Height and Weight
1) Height : Gravitational potential energy is greater when the height is
greater
2m
More Gravitational potential Energy
1m
Less Gravitational potential Energy
Types of Energy
2) Weight : Gravitational potential energy is greater when the weight of
the object is greater.
4N
2N
2m
2m
More Gravitational potential Energy Less Gravitational potential Energy
Types of Energy
Mechanical energy is energy due to the position of something or
the movement of something.
•Mechanical energy can be potential- due to the position
• Or kinetic - due to the movement of something
• Or the sum of the two ( Kinetic + Potential )
The falling ball has Mechanical
energy due to it’s position and
movement
Law of conservation of energy
The Law of conservation of energy states that
Energy cannot be created or destroyed
It can be transformed from one form to another, but the total
amount of energy never changes
Changing energy from one form to another is called
energy transformation.
Energy Transformations
A battery converts Chemical to
Electrical energy
When you burn gas you convert
Chemical energy to heat energy and
light energy
Energy Transformations
A light bulb burning converts
electrical energy to Light energy
and Heat energy
A speaker converts electrical energy
to Sound energy and Movement
energy
Energy Transformations
A power plant at a dam converts
mechanical energy to Electrical
energy
Remember
The Law of conservation of energy states that
Energy cannot be created or destroyed
It can be transformed from one form to another, but the total
amount of energy never changes
Changing energy from one form to another is called
energy transformation.
Remember!!!
All matter in the universe is composed of tiny particles
Tiny
Particles
Matter
These particles are called Atoms
Atom
Heat
SPS7. Students will relate transformations and
flow of energy within a system.
a. Identify energy transformations within a system
(e.g. lighting of a match).
b. Investigate molecular motion as it relates to
thermal energy changes in terms of conduction,
convection, and radiation.
c. Determine the heat capacity of a substance
using mass, specific heat, and temperature.
Temperature and Heat are different!!!
• Temperature is the measure of the average
kinetic energy of the particles in an object.
• Heat is the transfer of this kinetic energy from
one object to another due to the difference in
temperature between the objects.
• Heat transfer continues until both objects
have the same temperature.
Conduction
• 1) The transfer of energy as heat between
particles as they collide within a substance or
between two objects in contact is called
Conduction
Convection
• The transfer of energy by the movement of
fluids with different temperatures is called
Convection
Radiation
• The transfer of energy by electromagnetic
waves is called Radiation
Specific Heat
• The Specific heat of an object is the amount of
heat energy transfer needed to raise the
temperature of 1 Kg of the substance by 1
degree.
• The higher the specific heat of a substance,
the longer it retains heat.
Figure 3
Section 16.1
Specific Heat
Q = m x c x ∆T
Temperature
Absorbed
Specific heat
Lower specific heat
1°C
Specific heat
Temperature
Absorbs
Hot
Mass
Specific heat
Energy
Slower /Faster
Higher/ Lower
Cold
Change
Faster
Decrease
1 kg
Energy
Same
Calorimeter
∆T
!!!! Questions!!!!
1)Which of the following is not used to calculate kinetic energy?
a. mass c. height
b. weight d. velocity
2) Which of the following is not used to calculate potential
energy?
a. mass c. height
b. gravitational acceleration d. velocity
3) Thermal energy is measured in ______.
a. joules b. N c. ºC d. j/kg
!!!! Questions!!!!
4) The ______ energy of an object increases with its height.
a. chemical c. thermal
b. kinetic d. potential
5)The kinetic energy of an object increases as its ______ increases.
a. height above Earth c. potential energy
b. velocity d. volume
6) Mechanical energy is the total kinetic and ______ energies in a system
a. thermal b. chemical c. potential d. electrical
!!!! Questions!!!!
7) The law of ______ states that energy in a system can change forms but
can never be
created or destroyed.
a. conversion of energy c. conservation of energy
b. consecration of energy d. construction of energy