What is Energy? Flashcards
To know stuff aboot the energies, eh. (Canadian Accent)
What’s Energy?
Energy is the ability to do work. Energy can be present in an object when moving or not, and transfers between objects upon impacts.
How’s Energy Measured?
Because energy is the ability to do work and work is measured in joules.
What’s Potential Energy?
When you stretch a band, for example, the energy from the stretching stays in the band and leave it once released.
Two types of Potential Energy
Elastic Potential Energy is the first, and that is the one demonstrated in the rubber band example, and the second one; Gravitation Potential Energy, is anything that can fall as a result of gravity.
Gravitational Potential Energy Formula
grav. PE=massfree-fall accelerationheight or
PE=mgh. Notice that mg is the weight of the object in newtons, which as the same as gravitational force. So the equation is basically force*distance like the work equation.
What is Kinetic Energy?
The energy of something in motion.
Kinetic Energy Formila
KE=1/2mv^2 or
KE=1/2massspeed squared
Mechanical Energy
The sum of the potential and kinetic energy in a system.
Chemical Reactions and Energy
In a chemical reaction, bonds break apart. Both the breaking and formation of bonds involves changes in energy.
Energy for the Body
We get energy from the food and plants we eat, but where do those get energy? Plants get energy from the sun through a process called photosynthesis.
Sun’s Energy
The sun receives it’s energy by performing nuclear fusion, the process in which two light nuclei merge into a larger one.
Electricity
Our lights and appliances are powered by electricity, the result of the flow of charged particles moving through wires and conducting material.
Moving electrons also generate magnetic fields which can power special motors and other devices.
Lightning and Thunder
Lightning is caused by electrons traveling through the air between the ground and a thundercloud. Lightning is energy in the form of light, and a thunderclap is energy in the form of sound.
Light
Light can carry energy across an empty space. An asphalt surface on a bright day is hotter where light is shining directly at it then where it is in the shade. Light travels from the sun across space in electromagnetic waves. Light is split into a spectrum of colors which is what humans see, with light at one end closer to ultraviolet radiation and red at the left end closer to infrared radiation.
