What is Work and Energy?
The formula to calculate Work
Work = F x d
(Force times distance)
The type of energy involved in breaking apart the center of an atom:
Nuclear Energy
You are standing outside in freezing weather and begin rubbing your hands together for warmth:
Kinetic/Mechanical --> Thermal
When two nuclei are forced together in this type of nuclear reaction:
Fusion
What type of energy does a cup sitting on a table have and why?
The cup has gravitational potential energy due to its weight and position above the ground. It it not in motion, so it does not have Kinetic Energy.
The formula to calculate Kinetic Energy
KE = (1/2)mv2
Chemical Energy
You drop a penny from the top of a tall building:
When a nucleus is split apart:
Nuclear Fission
What is the type of energy associated with a change in the shape of an object? Give an example:
Elastic Potential Energy
Example: Stretching a rubber band changes its shape, giving it elastic potential energy
The units used for Work, Energy, and Power
Work - Joules
Energy - Joules
Power - Watts
The total energy of the particles in an object which are constantly in motion. The faster the particles move, the greater their kinetic energy, and the higher the temperature will be:
Thermal Energy
Nuclear fusion reactions in the sun generate light which reaches Earth, providing plants with one of the necessary components for photosynthesis:
Nuclear --> Electromagnetic --> Chemical
The universal law that states that energy cannot be created or destroyed:
The Law of Conservation of Energy
An object with a mass of 1 kilogram is resting on a shelf 2 meters above the ground. Approximately how much gravitational potential energy does the object have?
PE = mgh
PE = (1)(9.81)(2)
PE = Approximately 20 J
(19.62 J)
The formula used to calculate Gravitational Potential Energy:
PE = mgh
m = mass
g = gravitational acceleration (9.81m/s2 on Earth)
h = height
The type of energy which is transmitted through waves and do not require a medium through which to travel:
Electromagnetic Energy
You plug an electric toaster into the outlet in the wall. The bread is cooked. Once the toast is ready, the bread shoots upward by a mechanical arm.
Name the energy transformations:
Electrical --> Thermal --> Kinetic (Mechanical)
In a swinging pendulum, the point at which the pendulum has the least Potential Energy would be:
In the middle/at the bottom of the pendulum's swing
A machine does 200 Joules of Work on an object in 10 seconds. How much Power does the machine exhibit?
Power = Work / Time
Power = 200 J / 10 secs
Power = 20 Watts
A bowling ball with a mass of 4 kg is rolling down the alley with a velocity of 3m/s. What is the ball's Kinetic Energy?
KE = (1/2) 4 (3)2
KE = 18 J
The sum of the total Kinetic and Potential Energy of an object is equal to its:
Mechanical Energy
Example: An object with 10 J of Kinetic Energy and 5 J of Gravitational Potential Energy would have 15 J of Mechanical Energy.
Water from a river drops off the edge of a waterfall, falling through an electric turbine generator. The electric company sends that energy to people's homes, where a light switch is turned on.
Gravitational Potential --> Kinetic (Mechanical) --> Electrical --> Electromagnetic
Mr. Marra rolls the Come-Back Can with 10 J of Kinetic Energy. As the can rolls, the rubber band inside twists until the can comes to a stop.
How much Elastic Potential Energy would be stored in the rubber band at the end of the can's journey? (Assume no energy is lost to friction).
10 J
(Energy is conserved)
Name at least 5 of the 7 types of Electromagnetic Radiation:
Radio Waves, Microwaves, Infrared Waves, Visible Light, Ultraviolet, X-Rays, and Gamma Rays