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Unformatted text preview: vation than in the textbook see “Theory of Relativity” by W. Pauli (Pergamon
NY 1958) pages 9497.
The Doppler formula for the frequency of the reﬂected wave is
fr = f 1+
1− v
c
v
c
v
≈f 1+2
.
c Thus
v
fr − f = 2 f
c
v= fr − f
c
2f In our case fr < f so the car is moving away. The speed is the magnitude
of the above
v  = 2 × 103
3 × 108 = 15ms−1 . = 54 km/hr
4 × 1010
−15 8 4. We have E = hf = hc so that λ = hc = 4×10 E×3×10 when E is in
λ
E
M eV and λ is in meters. This means that with E = 1.24 × 105 eV λ = 10 pm.
5. The fraction left decreases exponetially with time. If T is the half life,
t
t
after time t the fraction of the isotope left is 2− T .In our case T = 3 = 4 .
9
12 1
Thus 2−4 = 16 of the isotope is left.
6. We use E = mc2 so that m= E
3 × 106 × 1.6 × 10−19
=
= 5.3 × 10−30 kg
2
c
(3 × 108 )2 2...
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This note was uploaded on 02/01/2013 for the course PHY 114 taught by Professor Jordan during the Spring '08 term at Rochester.
 Spring '08
 Jordan
 Physics

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