We see two stars separated by one degree on the celestial sphere. What can we infer about these stars?
A) They are very close together in space.
B) They have similar luminosities.
C) They rise and set at about the same time.
D) They were born about the same time.
C) They rise and set at about the same time.
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The diameter of the sun is 1.39*109 m. Estimate the percentage of the total radiation emitted by the sun, which approximates a blackbody at 5760 K, that is actually intercepted by the Earth. Of the total radiation falling on the Earth, about 70% falls on the ocean. Estimate the amount of radiation from the sun that falls on land, and then estimate the ratio of energy currently used worldwide and the amount of terrestrial solar energy that is available. Discuss why all of the energy cannot be harnessed.
GIVEN • Diameter of sun (Ds)= 1.39*109 m • Sun is approximate black body at temperature (Ts) =5760 K • 70% of radiation falls on the ocean. • Diameter of the earth (De)= 1.27*107 m • Distance between sun and earth (Rse )=1.53*1011 m FIND • Amount of radiation from sun that falls on land • Ratio of energy currently used worldwide and the amount of terrestrial solar energy that is available. • Discuss why all energy cannot be harnessed. ASSUMPTIONS • The sun’s radiation is assumed as ideal black body radiation.
Calculate the average force a bumper would have to exert to bring a 1200-kg car to rest in 15 cm when the car had an initial speed of 2.0 m/s (about 4.5 mph)
A) 1.8 × 104 N B) 1.6 × 104 N C) 5.4 × 104 N D) 6.5 × 105 N E) 3.2 × 104 N
A car travels in a due northerly direction at a speed of 55 km/h. The traces of rain on the side windows of the car make an angle of 60 degrees with respect to the horizontal. If the rain is falling vertically with respect to the earth, what is the speed of the rain with respect to the earth?
a. 48 km/h b. 95 km/h c. 58 km/h d. 32 km/h e. 80 km/h
A(n) ______ style sheet can be applied to multiple HTML documents across a website.
A. internal B. inline C. external D. exterior