LECTURE 9.2 – E = mc2

Today’s Learning Targets LT 9.2 – I can explain why energy is released in a nuclear fusion/fission reaction and I can calculate the amount of energy released.

What are nuclear fusion and fission?

I. Nuclear Fusion Fusion – When two things combine into one Nuclear fusion is when two atomic nuclei fuse into one new atom

II. Nuclear Fission Fission – Splitting of an item into two Nuclear fission is when a very heavy nucleus splits into a smaller, more stable nucleus

What is Einstein’s Equation?

I. Conservation of Matter Matter cannot be created or destroyed, it only can change forms. Sometimes, when compounds react the mass of the atom is not the same as the mass of protons and neutrons alone. The lost mass is converted into energy!

II. The Equation E = energy (measured in Joules) m = mass (measured in kilograms) c = the speed of light, 3.0 x 108 m/s or 300,000,000

Class Example You have a 2 kg object. Calculate the amount of energy that would be produced if you were to convert all of this mass into energy. (c = 3.0 x 108 m/s)

Table Talk You have a 5 kg substance. How much energy would be produced if this mass was converted to energy? (c = 3.0 x 108)

Stop and Jot If you produced 500,000 J of energy when you converted the mass of a substance to energy, then what was the original mass of the substance? (c = 3.0 x 108)

Applications of E=mc2 If we know the energy associated with the loss of mater in the nucleus, then we can use this energy for both good and bad. Common examples: Nuclear energy Atomic Bomb Smoke detectors Radio-isotopes in medicine