As a star forms, the photosphere first appears:
A) when the planetary nebula is expelled.
B) when the protostar forms.
C) when contraction slows down.
D) when nuclear fires ignite.
E) when the star reaches the main sequence.
B
You might also like to view...
Our Sun is a star of spectral type ________
A) M B) F C) S D) G
When the potential energy of a satellite decreases
A) kinetic energy also decreases. B) its kinetic energy correspondingly increases. C) its distance from the orbiting body increases. D) none of the above
A 60. gram toy rocket achieves a speed of 80. m/s after 3.0 s, when fired straight up. What is the average total force on the rocket during the 3 s?
A) 3.4 N B) 1.6 N C) 2.2 N D) 3.2 N E) 1.2 N
A woman is straining to lift a large crate, without success because it is too heavy
We denote the forces on the crate as follows: P is the upward force the woman exerts on the crate, C is the vertical contact force exerted on the crate by the floor, and W is the weight of the crate. How are the magnitudes of these forces related while the woman is trying unsuccessfully to lift the crate? A) P + C = W B) P + C < W C) P + C > W D) P = C