Tuesday 1 June:

Key Concept(s) Today:

Journal:

L#93/95/96 (Relativity)

#93:1 - 3, 17, 18  #95: 1, 2, 6

#96: 1, 2, 5, 7

(due Today  1 June)

#98 (Half-Life): 1 - 4, 6, 7, 10, 14, 16, 19,   (due Thursday 3 June)

Projects:

Mouse Trap Car Friday 4 June

Final: Tues 8 June

3. Power Pt on Nobel Prize (Physics) 15 June

New Material:

• The Speed of Light is the same for all observers.

• However, Mass, Time and Length change.

• Mass, Time and Length will remain normal to the observer in their own reference frame. "Everything is relative"  (except light).

Relativity Factor:

• "c" is the speed of light "v" is the speed of the object in question

   

   

  For example, in space when an rocket reaches a speed of 0.999c,  its length was 1 meters, its mass was 1 kg and it traveled for 1 year (its time), what would we measure its

  a. length

  b. mass

  c. time

g = 1/ √1- (V²/c²)

 = 1 / √1- (0.999c²/c²)

= 1 / √1- (0.998) 

g= 1/√.002   -->  22.4 times

So,

Length is shorter

             1/22.4 or .045 meters

Mass is greater by 22.4 times =

                      22.4 meters

Time is greater by 22.4 times =

                      22.4 years

__

Half‑life:

The time it takes for ½ of the atoms to decay. If you have 200 atoms, how long will it take before you have 6 atoms left if the half-life is 15 days?

Start with  200 atoms

1^st ½ life: 100 atoms à 15 days

2^nd ½ life: 50 atoms à 30 days

3^rd ½ life: 25 atoms à 45 days

4^th ½ life: 12.5 atoms à 60 days

5^th ½ life: 6 atoms à 75 days

_

Final: Tues 8 June

Turn in Tex Books by 8 June

Photoelectric Effect (PEE): If a beam of light is pointed at the negative end of a pair of charged plates, a current is produced. Each photon of blue light released an electron. But red photons did not.

·       The maximum kinetic energy K of the photoelectrons as a function of the frequency of incident light?

Nuclear Reactions

The following are conserved in a nuclear reactions:

    r (momentum) , electrical charge and nucleons

Fusion (combining):

               4 ¹₁Hà  ⁴₂He + energy (E = mc²)

 Difference in mass = 0.048 x 10^-27kg à E = mc²

à  E = (.048 x 10^-27)(3 x 10⁸)²

                             à E = 0.43 x 10^-11 J

Fission: (breaking apart):

q   Beta Decay:

q   (Beta-minus):                           ­­_

 ¹₀N  à       P+    +     e^-         +    h         +  Q

           neutron à  proton  + electron + Anti-neutrino + KE

q   Alpha Decay (Helium nucleus w/o electrons):

  ²³⁸₉₂U  à ²³⁴₉₀Th   + ⁴₂He     + Q

 Uranium 238 à  Thorium 234 + Alpha + disintegration energy

          (Parent)     à      (Daughters)           + 4.3 MeV