Please answer all questions.
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| 1 | |
A certain strain of bacteria doubles in number each 20 days. Two of these bacteria are placed on a spaceship and sent away from the Earth for 100 Earth-days as measured in their proper frame. During this time, the speed of the ship is 0.9950c. How many bacteria are aboard when the ship lands on the Earth? |
| | A) | 32 |
| | B) | 64 |
| | C) | 10 |
| | D) | 2000 |
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| 2 | |
A certain light source sends out 2 x 1015 pulses each second. As a spaceship travels parallel to the Earth's surface with a speed of 0.90c, it uses this source to send pulses to the Earth. The pulses are sent perpendicular to the path of the ship. How many pulses are recorded on Earth each second? |
| | A) | 4.6 x 1015 pulses/s |
| | B) | 3.8 x 1014 pulses/s |
| | C) | 6.3 x 1015 pulses/s |
| | D) | 8.7 x 1014 pulses/s |
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| 3 | |
The insignia painted on the side of a spaceship is a circle with a line across it at 45° to the vertical. As the ship shoots past another ship in space, with a relative speed of 0.95c, the second ship observes the insignia. What angle does the observed line make to the vertical? |
| | A) | tan Q = 3.20 and Q = 72.7° |
| | B) | tan Q = 0.0975 and Q = 5.6° |
| | C) | tan Q = 0.312 and Q = 17.3° |
| | D) | tan Q = 0.224 and Q = 12.6° |
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| 4 | |
As a spacecraft moving at 0.92c travels past an observer on Earth, the Earthbound observer and the occupants of the craft each start identical alarm clocks that are set to ring after 6.0 h have passed. According to the Earthling, what does the Earth clock read when the spacecraft clock rings? |
| | A) | 15.3 h |
| | B) | 2.4 h |
| | C) | 75.0 h |
| | D) | 39.1 h |
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| 5 | |
Find the speed and momentum of a proton (m=1.67 x 10-27kg) that has been accelerated through a potential difference of 2000 MV. (We call this a 2 GeV proton.) Give your answers to three significant figures. |
| | A) | a) 0.948 c, b) 1.49 x 10-18 kg·m/s |
| | B) | a) 2.06 c, b) 1.03 x 10-18 kg·m/s |
| | C) | a) 0.32 c, b) 4.75 x 10-18 kg·m/s |
| | D) | a) 0.898 c, b) 9.31 x 10-18 kg·m/s |
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| 6 | |
Compute the rest energy of an electron, ie, the energy equivalent of its mass, 9.11 x 10-31 kg. |
| | A) | 0.512 MeV = 8.2 x 10-14 J |
| | B) | 0.0017 eV = 2.73 x 10-22 J |
| | C) | 6.32 x 10-29 eV = 1.01 x 10-47 J |
| | D) | 5.12 x10-28 eV = 8.2 x 10-47 J |
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| 7 | |
Determine the speed of an electron having a kinetic energy of 1.0 x 105 eV (or equivalently 1.6 x 10-14J). |
| | A) | 1.6 x 108 m/s |
| | B) | 1.87 x 108 m/s |
| | C) | 2.5 x 1010 m/s |
| | D) | 2.9 x 108 m/s |
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| 8 | |
A proton (m=1.67 × 10-27 kg) is accelerated to a kinetic energy of 200 MeV. What is its speed at this energy? |
| | A) | 1.70 × 108 m/s |
| | B) | 9.79 × 107 m/s |
| | C) | 2.47 × 108 m/s |
| | D) | 6.25 × 108 m/s |
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| 9 | |
One consequence of the special theory of relativity is that |
| | A) | length is always constant to all observers. |
| | B) | conservation of momentum is not valid at speeds approaching the speed of light. |
| | C) | mass and energy are equivalent. |
| | D) | the wavelength of light changes with velocity. |
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| 10 | |
An object starts at rest and accelerates to a high speed. Which of the following properties does not change? |
| | A) | mass |
| | B) | kinetic energy |
| | C) | length |
| | D) | electric charge |
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