A giant star in another galaxy exploded 67 million years ago, forming a supernova. The event is observed by an astronomer on Earth
Estimate the speed at which the supernova (and its galaxy) recedes from Earth if the Hubble constant is 22 km/s per million light-years. (c = 3.00 × 108 m/s, 1 ly = 9.461 × 1015 m, 1 y = 3.156 × 107 s)
A) 4700 km/s B) 2700 km/s C) 1500 km/s D) 1200 km/s E) 670 km/s
C
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Although astronomers refer to the Galaxy's disk as rotating, the motion is really due to the ________ motion of each of the objects in the disk
Fill in the blank(s) with correct word
Two pistons push down on the fluid filling two cylinders connected by a narrow hose, as shown in the figure. The area A1 is 1 square inch, and the area A2 is 10 square inches. A force of 4 pounds is exerted downward on piston 1, as shown
 The force F2 in pounds needed to keep piston 2 in place is a. 0.25. b. 0.4. c. 4. d. 10. e. 40.Two large equipotent surfaces are flat and parallel and separated by a relatively small distance compared to their size. One surface is at 25.0 V and the other is at 33.0 V. The surfaces are 1.25 cm apart. What is the magnitude of the electric field midway between the surfaces?
A. 25.0 V/m
B. 29.0 V/m
C. 33.0 V/m
D. 
E. 
Two isotopes of the same element differ only in the number of protons
Indicate whether the statement is true or false