An electron (m = 9.11 × 10?31 kg) has a speed of 0.50c. Determine the difference between its relativistic kinetic energy and the kinetic energy calculated without considering relativity.

A. 3.0 × 10?15 J
B. 2.0 × 10?15 J
C. 1.5 × 10?15 J
D. 2.4 × 10?15 J
E. 1.8 × 10?15 J


Answer: D

Physics & Space Science

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Imagine an advanced civilization living on a planet orbiting at a distance of 10 AU (1.5 billion kilometers) from a close binary star system that consists of a 15 MSun red giant star and a 10 MSun black hole. The black hole is surrounded by an accretion disk. One foolhardy day, a daring individual in their space force (let's call him Major Tom) decides to become the first of his species to cross the event horizon of the black hole. To add to the drama, he decides to go in wearing only a thin space suit, which offers no shielding against radiation, no cushioning against any forces, and so on. Which of the following is most likely to kill him first (or at least to start the process of killing him first)?

A) x-rays from the accretion disk B) tidal forces due to the black hole C) the crush of gravity at the singularity embedded within the black hole D) the sucking force from the black hole, which will cause his head to explode

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I use a rope 1.00-m-long to swing a 1.00-kg weight around my head. The tension in the rope is 20.0 N. In half a revolution how much work is done by the rope on the weight?

a. 20.0 J
b. 31.4 J
c. 123 J
d. 0

Physics & Space Science

If the period of a pendulum is tripled, then by factor is the length of the string increased?

a. 3 b. 6 c. 9 d. 1/3

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At what angle above the horizon would the sun appear if its reflected light from a lake, viewed at the same time, were completely polarized? (n water = 1.333)

A. 53.12
B. 36.88
C. 48.75
D. 41.25
E. 23.52

Physics & Space Science