What happens to the visible light radiated by stars located within a dusty gas cloud?
A) It is blocked by dust and its energy is thereby lost.
B) It is absorbed by dust, which heats the dust grains so that they emit the absorbed energy as infrared light.
C) It is reflected by dust back to the star from whence it came.
D) It passes through the cloud unaffected.
B
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Which of the following indicates that the Sun must be gas from its surface to its center?
A) Its low density and high temperature B) Its limited gravitational force C) Its hot spots on the photosphere D) Its weak magnetic field and small diameter
Which sequence of formation is most likely to be correct, oldest to youngest?
A) globular clusters, open clusters, OB associations B) Population I stars, population II stars, population III stars C) halo, spiral arms, globular clusters D) planetary nebulae, Population I stars, population II stars E) emission nebulae, planetary nebulae, dark nebulae
The heat of vaporization of ethyl alcohol Lv is about 200 cal/g. That means that 1 gram of this refrigerant upon vaporization would release
A) less then 200 calories. B) 200 calories. C) more than 200 calories.
Projectile Motion: A hockey puck slides off the edge of a platform with an initial velocity of 20 m/s horizontally. The height of the platform above the ground is 2.0 m. What is the magnitude of the velocity of the puck just before it touches the ground? You can neglect air resistance.
A. 21 m/s B. 22 m/s C. 24 m/s D. 25 m/s E. 6.3 m/s