Protostars are difficult to observe because
a. the protostar stage is very short.
b. they are surrounded by cocoons of gas and dust.
c. they radiate mainly in the infrared.
d. the protostar stage is very short, they are surrounded by cocoons of gas and dust, and they radiate mainly in the infrared.
e. they are all so far away that the light hasn't reached us yet.
d
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A long nonconducting cylinder (radius = 6.0 mm) has a nonuniform volume charge density given by ?r2, where ? = 6.2 mC/m5 and r is the distance from the axis of the cylinder. What is the magnitude of the electric field at a point 2.0 mm from the axis?
a. 1.4 N/C b. 1.6 N/C c. 1.8 N/C d. 2.0 N/C e. 5.4 N/C
Where would you expect terrestrial planets to form in the solar nebula?
a. within the innermost regions (within about the inner 0.3 AU) b. anywhere between the innermost regions (within about the inner 0.3 AU) and the frost line c. anywhere outside the innermost regions (within about the inner 0.3 AU) d. anywhere outside the frost line
A car is 200 m from a stop sign and traveling toward the sign at 40.0 m/s
At this time, the driver suddenly realizes that she must stop the car. If it takes 0.200 s for the driver to apply the brakes, what must be the magnitude of the constant acceleration of the car after the brakes are applied so that the car will come to rest at the stop sign? A) 2.89 m/s2 B) 3.89 m/s2 C) 4.17 m/s2 D) 3.42 m/s2 E) 2.08 m/s2
The precision and number of significant figures in 1.003 km is
A. precision = .0001 km, significant figure = 4. B. precision = .001 km, significant figure = 4. C. precision = .0001 km, significant figure = 3. D. precision = .001 km, significant figure = 3. E. precision = .0001 km, significant figure = 2.