The period-luminosity relation for Cepheid variables was discovered in 1908 by
A) William Herschel.
B) Henrietta Leavitt.
C) Harlow Shapley.
D) Heber Curtiss.
E) Edwin Hubble.
B
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In titanium alloys called “mill annealed,” the alloy is not _________, it is only annealed after deformation.
Fill in the blank(s) with the appropriate word(s).
If during a given physical process the only force acting on an object is friction, which of the following must be assumed in regard to the object's kinetic energy?
a. decreases c. remains constant b. increases d. cannot tell from the information given
A charge of 20 nC is distributed uniformly along the x axis from x = -2.0 m to x = +2.0 m. What is the electric potential (relative to zero at infinity) at the point x = 5.0 m on the x axis?
a. 57 V b. 48 V c. 38 V d. 67 V e. 100 V
A flask brim filled with water is on a weighing scale. If you float a piece of wood in it, after spillage away from the scale, the scale reading will be
A) less. B) the same. C) greater.