there are 2 forms of energy… kinetic energy potential energy
TRANSCRIPT
There are 2 forms of energy…
Kinetic EnergyPotential Energy
We already know that Kinetic Energy is the energy
Of motion.
But what if something is Not moving?
Potential energy is stored Energy.
One kind of potential energy isEnergy due to its position
On earth.
This is gravitational Potential energy.
PE = mgh
If Cal lifts a 2 kg textbook fromThe floor to a shelf 2.1 m aboveThe floor. What is the book’s
Potential energy relative to the Floor? What is the potential energy
Relative to his head if he is 1.65 m tall?
41.2 J 8.82J
Elastic potential energy is the Potential energy of a
Stretched or compressed spring.
The spring constant (k) is a Parameter that expresses howResistant a spring is to being
Compressed or stretched.
PEelastic = ½ kx2
The staples inside a stapler are Kept in place with a spring with aRelaxed length of 0.115m. If theSpring constant is 51 N/m, how
Much PE is stored when the Spring is stretched to 0.150m?
0.031 J
Mechanical Energy is the sumOf kinetic energy and all forms
Of potential energy.
ME = KE + ΣPE
Einstein recognized yet anotherForm of potential energy:
Mass Itself!
He said that mass, by its veryNature, is just one manifestation
Of Energy.
E = mc2
The law of conservation of Energy states that energy cannot
Be created or destroyed, onlyTransferred.
MEi = MEf
The law of conservation of Matter states that matter
Cannot be created not destroyed.
As far as you are allowed to know.
A large chunk of ice with a massOf 15 kg falls from a roof 8 m Above the ground. Find the
Kinetic Energy of the ice whenIt reaches the ground. What is The speed of the ice when it
Reaches the ground?
1180 J 12.5 m/s
An elastic collision is a Collision in which the total
Momentum and the total kineticEnergy remain constant.
m1v1i + m2v2i = m1v1f + m2v2f
½m1v1i2 + ½m2v2i
2 =
½m1v1f2 + ½m2v2f
2
A perfectly inelastic collision is aCollision in which two objectsStick together and move with
A common velocity afterColliding.
In an elastic collision, the kineticEnergy is slightly decreased.
Usually it is converted to Thermal and sound energy.
