Postulates of Special Relativity are

The speed of light in freespace has the same value c in all inertial frames, The Laws of physics are the same in all inertial frames

Modern physics concerns

Quantum theories, Physics from 1900 and later, Special and General Relativity

If a galaxy recedes from us at 0.1c, a 100 nm emission line at source would be measured on Earth as

111 nm = 100 nm / \sqrt{\frac{.9}{1.1}}

What is the total energy of a mass 137 MeV/c2 pion moving at 0.5 c? E=

\sqrt{\left(79MeV\right)^2+\left(137MeV\right)^2}= 158 MeV

What is the momentum of a mass 137 MeV/c2 pion moving at 0.5c?

\frac{\left(137\cdot.5\right)}{\sqrt{1-.5^2}}=79 MeV/c

Standard classical conservation laws are modified as follows for relativistic particle collisions:

Relativistic total energy is conserved, including rest energy

A K0 has a proper lifetime of 50 ns. It makes a track 300 m long in the lab frame. Its velocity u can be found from:

1000 ns = \frac{50ns}{\sqrt{1-\frac{uu}{cc}}}

studbud

Modern Physics Exam 1

11 termsStudBud Administration40 plays

Imported from external platform

Flashcards11 cardsFPractice quizPHost liveL

Questions 11

Answers

1
Postulates of Special Relativity are
The speed of light in freespace has the same value c in all inertial frames
The Laws of physics are the same in all inertial frames
The ether maintains the same structure in all inertial frames
Linear momentum and kinetic energy are invariant in all inertial frames
2
Modern physics concerns
Quantum theories
Physics from 1900 and later
Special and General Relativity
Anything complicated enough to require a computer to calculate
3
If a ship is 100 m according to O' on the ship, and moves at 0.6c relative to observer O, O sees length as
100\sqrt{1-0.6^2} = 80 m
100/\sqrt{1-0.6^2}= 125 m
100 m because length is invariant
100/\sqrt{1-.6}= 158 m
4
The Michelson-Morley experiment is seen as:
all of the above
evidence that the ether does not exist
the experiment that led to Lorentz developing his transformations
evidence that Einstein's special theory of relativity is correct
5
If a galaxy recedes from us at 0.1c, a 100 nm emission line at source would be measured on Earth as
94.9 nm = 100 nm * \sqrt{\left(1-0.1\right)}
111 nm = 100 nm / \sqrt{\frac{.9}{1.1}}
90.5 nm = 100 nm * \sqrt{\frac{.9}{1.1}}
100 nm because light doesn't age
6
What is the total energy of a mass 137 MeV/c² pion moving at 0.5 c? E=
79 MeV + 137 MeV = 216 MeV
137 /\sqrt{1-\frac{79^2}{137^2}}=168 MeV
79 MeV
\sqrt{\left(79MeV\right)^2+\left(137MeV\right)^2}= 158 MeV
7
What is the momentum of a mass 137 MeV/c² pion moving at 0.5c?
137 MeV
\frac{\left(137\cdot.5\right)}{\sqrt{1-.5^2}}=79 MeV/c
137MeV*0.5C=68.5 MeVc
137\sqrt{\left(1+0.5^2\right)}=153 MeV/c
8
Standard classical conservation laws are modified as follows for relativistic particle collisions:
Relativistic total energy is conserved, including rest energy
Energy and momentum cannot both be known precisely at the same time
Energy is still conserved but momentum is just a thing Newton made up
Momentum and energy conservation only work in the rest frame
9
Proper length is measured by an observer for whom the object being measured
has no mass
has excellent table manners
is at rest
doesn't age
10
A K⁰ has a proper lifetime of 50 ns. It makes a track 300 m long in the lab frame. Its velocity u can be found from:
1000 ns = \frac{50ns}{\sqrt{1-\frac{uu}{cc}}}
1000 ns = \frac{50ns}{1-\frac{u}{c}}
50 ns = \frac{1000ns}{1+\frac{u}{c}}
50 ns = \frac{1000ns}{\sqrt{1-\frac{uu}{cc}}}
11
What is the kinetic energy possessed by our mass 137 Me/c2 pion moving at 0.5c?
158 + 137 = 295 MeV
158 MeV
158 - 137 = 21 MeV
nan

Modern Physics Exam 1 Flashcards | StudBud