Which of the following is the most precise method for measuring the mass of a galaxy?
A) The parallax method
B) The rotation curve method
C) The visual field test
D) Colorimetry
B
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If a rectangular area is rotated in a uniform electric field from the position where the maximum electric flux goes through it to an orientation where only half the flux goes through it, what has been the angle of rotation?
A) 45° B) 26.6° C) 90° D) 30° E) 60°
Three boxes in contact rest side-by-side on a smooth, horizontal floor. Their masses are 5.0-kg, 3.0-kg, and 2.0-kg, with the 3.0-kg box in the center. A force of 50 N pushes on the 5.0-kg box, which pushes against the other two boxes
(a) Draw the free-body diagrams for each of the boxes. (b) What magnitude force does the 3.0-kg box exert on the 5.0-kg box? (c) What magnitude force does the 3.0-kg box exert on the 2.0-kg box?
In composition and density, the asteroids most resemble:
A) comets. B) the Sun. C) jovian moons. D) pieces of terrestrial planets. E) Kuiper Belt objects like Pluto.
An ideal transformer with 120 turns in its secondary supplies 12 V at 220 mA to a toy train. The primary is connected across a 120-V wall outlet
(a) How many turns are in the primary? (b) What is the primary current? (c) What power is delivered by the wall outlet?