Presentation on theme: "Energy Every observable change requires energy."— Presentation transcript:
1 Energy Every observable change requires energy. Energy comes in several different forms (food, electrical, solar, chemical), and can be converted from one form to another.
2 Kinetic energy Energy associated with motion KE = ½ mv2 units are Joulesmass MUST be in kgvelocity MUST be in m/sExample:What is the kinetic energy of a baseball moving at a speed of 40 m/s if the baseball has a mass of 0.15 kg?KE = ½ mv2KE = ½ (0.15 kg)(40 m/s)2KE = 120 J
3 Potential Energy:The energy stored in motionless objectsFour types:1. Elastic potential energy2. Chemical Potential EnergyStored by something that can stretch or compressEnergy is released when the object is allowed to return to its normal stateChemical bonds store energy.Breaking the bonds releases the energy
4 3. Electrical and Nuclear Potential Energy 4. Gravitational Potential EnergyElectrical-stored energy due to the position of electrical charges.Nuclear-energy stored in the nucleus of an atomAnything that can fall has stored GPEGPE = mghm = mass in kgg = gravitational acceleration (9.8 m/s2)h = height above the groundThe higher above the ground something is, the greater the GPEEX: Find the height of a baseball with a mass of 0.15 kg that has a GPE of 73.5 J.GPE = mgh73.5 J = (0.15 kg)(9.8 m/s2)hh = 50 m
5 Conservation of Energy: Energy is neither created nor destroyed as is changes from one form to anotherGPE = mgh= (2 kg)(9.8 m/s2)(10 m) = 196 J2 kgKE = 0 Jh = 10 mWhile the energy has changed form, the amount of energy has not changed. Energy has been conserved.KE = ½ mv2 =196 J2 kgGPE = 0 J