From laboratory measurements, we know that a particular spectral line formed by hydrogen appears at a wavelength of 486.1 nanometers (nm). The spectrum of a particular star shows the same hydrogen line appearing at a wavelength of 485.9 nm
What can we conclude? A) The star is moving toward us.
B) The star is moving away from us.
C) The star is getting hotter.
D) The star is getting colder.
E) The "star" actually is a planet.
A
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A mobile is made of identical objects of mass m suspended so that the lowest row has one object, the row above two objects, and the row above three objects. All the strings are at 45° angles. What is the average tension in the strings connecting the highest row to the ceiling?
A.
B.
C.
D.
E.
Beam ACB has a pin support at A and is supported at C by a steel column with a square cross section (E 5 190 GPa, b 5 42 mm) and height L 5 5.25 m. The column is pinned at C and fixed at D. The column must resist a load Q at B with a factor of safety of 2.0 with respect to the critical load. The maximum permissible value of Q is approximately:
(A) 3.0 kN
(B) 6.0 kN
(C) 9.4 kN
(D) 10.1 kN
Two horizontal pipes are the same length, but pipe B has twice the diameter of pipe A. Water undergoes viscous flow in both pipes, subject to the same pressure difference across the lengths of the pipes
If the flow rate in pipe A is Q, what is the flow rate in pipe B? A) 1/2Q B) 2Q C) 4Q D) 8Q E) 16Q
A thin, circular disk of radius 30.0 cm is oriented in the yz-plane with its center at the origin. The disk carries a total charge of +3.00 ?C distributed uniformly over its surface
Calculate the magnitude of the electric field due to the disk at the point x = 15.0 cm along the x-axis. (?0 = 8.85 × 10-12 C2/N ? m2) A) 9.95 × 105 N/C B) 4.98 × 105 N/C C) 3.31 × 105 N/C D) 2.49 × 105 N/C E) 1.99 × 105 N/C