How many galaxies are there in the observable universe?
A) about as many as the number of stars we see in the sky with our naked eyes
B) infinity
C) roughly a thousand times more than the number of stars in our galaxy
D) roughly (within a factor of 10 ) the same as the number of stars in our galaxy
E) about as many as the number of grains of sand on all the beaches on Earth
D
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A 0.20-kg object attached to the end of a string swings in a vertical circle (radius = 80 cm). At the top of the circle the speed of the object is 4.5 m/s. What is the magnitude of the tension in the string at this position?
a. 7.0 N b. 2.0 N c. 3.1 N d. 5.1 N e. 6.6 N
Charge of a uniform density (8.0 nC/m2) is distributed over the entire xy plane. A charge of uniform density (5.0 nC/m2) is distributed over the parallel plane defined by z = 2.0 m. Determine the magnitude of the electric field for any point with z = 1.0 m
a. 0.45 kN/C b. 0.17 kN/C c. 0.28 kN/C d. 0.73 kN/C e. 0.62 kN/C
What is the formula of a compound formed from the ions M2+ and X3-?
a. MX b. M3X2 c. M2X3 d. M6X6
A 1.8-kg block is projected up a rough 10° inclined plane. As the block slides up the incline, its acceleration is 3.8 m/s2 down the incline. What is the magnitude of the force of friction acting on the block?
a. 5.0 N b. 3.8 N c. 4.2 N d. 4.6 N e. 6.5 N