Transcript Warm Up - Muroc Joint Unified School District

Warm Up
1. What is the difference between an
element and a compound?
2. What is the difference between a
uniform and nonuniform mixture?
Reading Activity – Rd. p. 64-71
What I know
about energy
What I want to
know about
energy
What I learned
about energy
What is energy?
• Energy is – the ability to cause change.
• Energy can change – the temperature,
shape, speed or direction of an object.
• You can use the energy of your muscles –
to change the speed of a bicycle by
pedaling faster.
Energy Transformations And Uses
• Energy transformations – take place all around
you.
• When a car sits in the sun all day – the energy of
light waves change to a form of energy that
warms the car.
• Learning to make fires – the chemical energy in
wood is used to cook, stay warm and provide
light.
• Today, electrical energy – is changed into
thermal energy that warms your home.
Brainstorming Energy
• Brainstorm ways that you use energy
every day. First group to list 5 ways gets a
point…
Kinetic Energy
• Kinetic energy – is the energy provided by
an object in motion.
• Examples – a football thrown by a
quarterback or a skydiver falling towards
Earth,
How much kinetic energy?
• Not all moving objects – have the same
amount of kinetic energy.
• The amount of kinetic energy – an object
has depends on the mass and speed of an
object.
• Visualizing Kinetic Energy: p. 67, A and B
Potential Energy
• Potential energy – is energy that comes
from position or condition.
• Potential energy IS NOT – energy that
comes from motion.
• Example – a skier at the top of a hill has
potential energy. Even though the skier is
not moving, there is the potential to move.
Relating Kinetic and Potential
Energy
• There is a direct relationship – between the
amount of potential energy an object has and
the amount of energy that can be transformed
into kinetic energy.
• When a book is placed on the edge of a table –
it has potential energy.
• When the book is pushed off – the energy
becomes kinetic.
• A book placed on a higher shelf – has more
potential energy and therefore more kinetic
energy as it falls than it would have if it were on
a lower shelf.
Conserving Energy
•
•
•
1.
2.
3.
4.
Law of conservation of energy – energy cannot be
created or destroyed.
Energy – can only be transformed from one form into
another.
Energy in the case of a soccer ball:
The soccer player has chemical energy in her muscles
from eating food.
The chemical energy is released as she swings her
leg.
Her leg now has potential energy.
When her foot kicks the ball, her foot’s kinetic energy is
transferred to the ball and the ball is set in motion.
Class Activity - Charades
Potential Energy
Kinetic Energy
Check for Understanding
• 1. State the law of conservation of energy in
your own words.
• 2. Compare and contrast potential and kinetic
energy.
HW: Science Journal
p. 71 #3 – You get up in the morning, get dressed,
eat breakfast, walk to the bus stop and ride to
school. List three different energy
transformations that have taken place.