Energy and its Energy and its formsforms

Energy and its Energy and its formsforms

Energy is the ability to do workEnergy is the ability to do work

Work is the transfer of energyWork is the transfer of energy

Kinetic Energy• The energy of motion• Kinetic energy depends on its mass

and speed• Kinetic Energy = 1/2mv2

• Example – A .10kg bird is flying at a constant speed of 8.0 m/s What is the bird’s kinetic energy?

• m = .10kg v = 8.0 m/s½(.10kg)(8.0 m/s)2 =3.2J

Potential Energy• Two types

• Gravitational depends on mass, height and gravity. Height is relative to a point

• GPE = mgh

• Elastic Potential energy of an object that is stretched or compressed.

• A diver at the top of a 10 m board has a mass of 50 kg. What is her potential energy relative to the water below?

–M= 50kg g= 9.8m/s2 h= 10m

–(50kg)(9.8m/s)(10m)=4900J

Forms of energy• Mechanical – energy associated with

position and motion of everyday objects

• Thermal – Total kinetic and potential energy of all particles of an object

• Chemical – is the energy stored in the chemical bonds in compounds

Forms of energy• Electrical – energy associated with

electrical charges

• Electromagnetic – Energy that travels through space in waves (visable light and x-rays are examples)

• Nuclear – energy stored in atomic nuclei.

• Nuclear power plants produce electricity• Atoms are split and the heat generated is

used to heat water• Steam Spins turbines making electricity