Background radiation from cosmic rays and radioactive nuclei in our surroundings is about 0.13 rem/year. Suppose we assume this all comes from cosmic rays which have an RBE factor of 1.0 . The RBE factor for the most dangerous types of radiation is 20 . How many rads of the most dangerous radiation could a 100-year-old person have been exposed to in her lifetime without having gone over the
recommended limit of 0.5 rem/year?
a. 0.37
b. 0.50
c. 1.85
d. 13
e. 37
c
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Which of the following statements is true of stars?
A) Stars should have very low densities to support their own weight. B) Stars should have very low temperatures to support their own weight. C) The pressure of a gas near the surface of a star does not need to be high for stability. D) The temperature of a gas near the center of a star does not need to be high for stability.
At the center of our Galaxy lies
A) a quasar. B) a huge emission nebula. C) an intensely bright visible superstar. D) the largest of all globular clusters. E) a black hole of millions of solar masses.
The index of refraction for red light in water is 1.331 and for blue light is 1.340 . If a ray of white light enters the water at an angle of incidence of 83.00°, what are the underwater angles of refraction for the blue and red components of the light?
A 60.0-kg satellite is in orbit a distance 2000 km above the surface of the earth. The mass of the earth is 5.976 x 1024 kg and the radius of the earth is 6.378 × 106 m
(a) What is the change in the gravitational potential energy if the satellite moves to a circular orbit 5000 km above the surface of the earth? (b) What is the change in kinetic energy if the satellite moves to a circular orbit 5000 km above the surface of the earth? (c) How much work must be done on the satellite to move it to a circular orbit 5000 km above the surface of the earth?