Which of the sounds matches the real universe?
A: the one with 2% of the density in atoms
B: the one with 4% of the density in atoms
C: the one with 8% of the density in atoms
Ans: B: the one with 4% of the density in atoms
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A star more luminous than our Sun will have a habitable zone that is
A) narrower and farther from the star than the habitable zone of the Sun B) narrower and closer to the star than the habitable zone of the Sun C) wider and farther from the star than the habitable zone of the Sun D) wider and closer to the star than the habitable zone of the Sun
A weightless spring of force constant 2.50 N/cm is 15.0 cm long when nothing is attached to it. It is now used to pull horizontally on a 12.5 kg box on a smooth horizontal floor
You observe that the box starts from rest and moves 96.0 cm during the first 1.60 s of its motion. How long is the spring during this motion?
Energy and Momentum: An 8.0-g bullet is suddenly shot into a 4.0-kg block, at rest on a frictionless horizontal surface, as shown in the figure. The bullet remains lodged in the block. The block then moves against a spring and compresses it by 8.9 cm. The force constant (spring constant) of the spring is 1400 N/m. What is the magnitude of the impulse on the block (including the bullet inside) due to the spring during the entire time interval during which the block compresses the spring?
A. 13 N ? s B. 12 N ? s C. 10 N ? s D. 8.3 N ? s E. 6.7 N ? s
A sack of potatoes weighing 200 N falls from an airplane. As the velocity of fall increases, air resistance also increases. When air resistance equals 200 N, the sack's acceleration becomes
A) 0 m/s2. B) 5 m/s2. C) 10 m/s2. D) infinite. E) none of the above