Energy What is Energy Energy is the ability
Energy
What is Energy �Energy is the ability to do work or cause change. ◦ “Work”? �One definition for work is “the transfer of energy”. �When one object does work on another, energy is transferred to that object. �Energy is measured in Joules (J) ◦ Just like work!
Potential Energy Stored energy due to the interaction between objects or particles. ◦ has the potential to cause change Gravitational forces Elastic forces Electrical forces Magnetic forces
Gravitational Potential Energy The ability to “fall” due to Earth’s gravitational force ◦ Depends on two things Mass of the object Distance (height) from Earth’s surface
Chemical Energy stored in chemical bonds ◦ Energy is released when bonds are broken ◦ Food: Energy is stored in the chemical bonds of the food molecules. When you eat, your body breaks those chemical bonds. Energy is released that your body uses to perform its functions!
Nuclear Energy Stored in the nucleus of an atom, released during nuclear reaction ◦ Fission – splitting atoms ◦ Fusion – joining atoms together
Kinetic Energy due to motion ◦ Depends on two things Mass of the object Velocity (speed) of the object
Electrical Energy carried by moving electrons ◦ Batteries ◦ Power Lines ◦ Lightning
Mechanical Energy associated with the motion or position of an object Sum of the kinetic and potential energy
Thermal Energy Total energy of the particles in an object ◦ Temperature – average kinetic energy of the molecules (how fast they are moving).
Energy Carried by Waves Wave: a disturbance that transfers energy from one place to another without transferring matter
Sound Energy carried by sound waves ◦ Energy causes particles to bump into one another, transferring the energy in a sound wave There can be no sound without particles…
Radiant Energy carried by electromagnetic waves (light) ◦ Visible Light ◦ Radio Waves, Microwaves, etc…
STOP HERE
What Happens to Energy? �If you set a pendulum in motion, will it continue to swing forever? ◦ No �Is the original energy lost? ◦ No �The energy is simply converted to other forms
Law of Conservation of Energy cannot be created or destroyed, only converted from one form to another. ◦ The total amount of energy is the same before and after any process!!! So what causes the pendulum to stop?
Energy Conversions At the top, you’ve given the pendulum gravitational potential energy When you release it…
Energy Conversions
Energy Conversions
Energy Conversions As the height decreases, PE decreases As it speeds up, KE increases The faster it goes, the more friction it encounters
Energy Conversions What happens to it on the way back up? ◦ KE PE On the way back, does it go up as high as it started? ◦ No Why not? ◦ Friction
Energy Conversions Each time, the maximum height is lower and lower ◦ Due to energy transferred to heat energy because of friction Eventually, it stops.
Energy Conversions PE Electrical KE KE
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