Power
By Levi Clancy for Student Reader on
updated
- Physics
- Calorimetrics
- Circuits
- Electricity and Magnetism
- Fluid Dynamics
- Fluid Statics
- Friction
- Human Eye
- Ideal Gas Law
- Interference and Diffraction
- Kinematics
- Mirrors and lenses
- Newton’s Law of Gravitation
- Newton’s laws of motion
- Optics
- Oscillations
- Physics of Breakdancing
- Polarization
- Power
- Thermal expansion
- Thermodynamic Systems
- Vectors
Power measures howquickly work gets done. For example, a force of 100J of work in 20 seconds is being done at a rate of 100J/20s = 5J/s. This is the power (P), and from sample calculation above the units are obviously J/s. This is defined as the watt, W, which should not be confused with the W which defines work.
Power = work/time = W/t
The faster work gets done, the greater the power. If there is constant v and force is parallel to path, then P = Fv
Energy is the ability to do work. Moving objects inherently have energy because they can crash into something and exert a force over a distance. Kinetic energy is this energy of motion.
Fd=.5mv2
W=.5mv2
KE = .5mv2
This assumes the initial speed of the object is 0. If it were not, then W = KEfinal - KEinitial.Wtotal = ΔKE.
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Potential energy is energy of an object due to position. There is gravitational, electrical, and elastic potential energy. Potential energy is placed on position in a gravitational field. ΔPEgrav=-Wby Fgrav=mgh. If the brick had fallen, it would have been -mgh.
PE = -mgh
Gravity is a conservative force.