Law of Energy
What does the law of conservation of energy state?
Energy cannot be created or destroyed, only transformed.
What is friction?
A force that resists motion between two surfaces.
What is work in science?
Transfer of energy by force and motion.
: Slide down a slide—what happens to energy?
Potential becomes kinetic, and some is lost as thermal energy.
In the swing model, where is kinetic energy highest?
At the bottom of the swing.
Can energy be destroyed?
No, it can only change forms.
What does friction do to energy?
Converts mechanical energy into thermal energy.
What is mechanical energy made of?
Kinetic energy + potential energy.
What happens when you brake on a bike?
Mechanical energy changes into thermal energy.
Where is potential energy highest?
At the highest point of the swing.
What happens when energy seems to “disappear”?
It’s transformed, often into thermal energy.
What materials reduce friction?
Grease, oil, graphite.
Write the mechanical energy formula.
ME = KE + PE.
Why do we say energy is “lost”?
Some becomes thermal and is no longer useful for motion.
What does the swing model show?
Energy constantly transforms between potential and kinetic.
What stays the same during energy transformations?
The total amount of energy.
What material does NOT reduce friction?
Cotton.
What does work do to energy?
It transfers energy between objects.
Is “lost” energy gone forever?
No—it’s just in a different form.
What is Katie’s claim about the ball experiment?
PE decreases and KE increases as the ball rolls down.
Give an example of energy transformation.
Mechanical energy → thermal energy when using brakes.
Why does a slide feel warm after going down?
Friction changes mechanical energy into heat.
Give an example of mechanical energy.
A moving swing or a rolling ball.
Where does “lost” energy usually go?
Into the environment as heat.
What evidence supports Katie's claim?
As height goes down, speed goes up, and total energy stays the same.