Throwbacks
Does air have mass
Yes
The ability to do work defines
Energy
What are we measuring if the unit is joules?
Energy or Work
You serve a volleyball with a mass of 10kg. The ball leaves your hand at 5m/s. How much energy does it have?
0.5 x 10 x 5 x 5 = 125J
How are the elements organized on the periodic table?
by atomic mass or the number of protons each element has
Protons, Neutrons, and Electrons make an
atom
The energy of an object in motion
Kinetic Energy
What forms of energy are observed when lighting a light bulb?
Light, Thermal, and Electric
If a 25kg box is dropped from a height of 4m, how much kinetic energy and thermal energy does it have after it hits the ground?
KE = 0J
GPE= 10 x 25 x 4 = 1000J
TE= 1000J
The from energy of objects that give off light (hint: the other word for light energy)
Radiant energy
Gravity acts on
Everything with mass
A person riding a bike down hill has
Both kinetic and potential energy
A car that turned all of its chemical energy into kinetic energy would sound like and have a temperature of . . .
Would be quiet and have no change in temperature
How can I calculate the height an object is dropped from if I know it’s mass and velocity?
Because a dropped objects KE can only be as much as its GPE.
This of course ignores air resistance, let's save that for college.
If something has a pH value of 3.0, we would say that it is . . .
acidic or an acid
Atoms that are bonded together
Molecules or Compounds
When throwing a ball into the air, where does the ball have the most potential energy?
At its highest point
Sunlight has no mass, does it have kinetic energy?
No, because kinetic energy must have mass; it’s in the formula.
What is the mass of an object that has 50000J of energy that is traveling at 25m/s?
50000J = 0.5 x m x 252
50000J/0.5 = m 252
100000/252 = m
160kg = m
What is something you see everyday that turns radiant energy into chemical energy?
Plants and trees
Mercury, Hydrogen, and Iodine are examples of
Elements
State the Law of Conservation of Energy
Energy isn’t created or destroyed, it is only transferred or transformed
How does mass affect the total amount of energy a system has?
More mass = more energy in the system
If a 50kg skater goes down a ramp that is 10.0m high, what will their velocity be at the bottom of the ramp?
GPE= 10 x 50 x 10 = 5000J
5000J = 0.5 x 50 x v2
5000J/25 = v2
Square root (200) = v
14m/s = v
Think about the Law of Conservation of Energy, why can cold blooded animals go longer without eating than warm blooded animals?
Cold blooded animals use the sun's rays to generate body heat vs. using their own chemical energy to do it. While warm blooded animals are always keeping their bodies warm and using their chemical energy.