What is the energy density in the magnetic field 25 cm from a long straight wire carrying a current of 12 A? (?0 = 4? × 10-7 T • m/A)
A) 7.3 × 10-5 J/m3
B) 3.6 × 10-4 J/m3
C) 3.7 × 10-5 J/m3
D) 1.2 × 10-4 J/m3
E) The density cannot be determined without knowing the volume.
C
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The two most important properties of any telescope are
A. the magnification and the light-gathering power. B. the light-gathering power and the length of the tube. C. the length of the tube and the magnification. D. the light-gathering power and the resolving power. E. the resolving power and the magnification.
Astronomers believe that the Moon did not differentiate to the same degree as Earth because:
A) the Moon was made of solid debris, not liquids like our hydrosphere. B) the meteors that hit the Moon were lighter than those that hit us, so did not generate as much heat on the surface. C) the less dense and smaller Moon did not have as much radioactivity as the larger Earth in its core. D) the Moon was formed after the Earth was, so its radioactivity was less. E) the Moon was made of very different materials than our mantle and crust.
The slope of a distance vs. time graph is the acceleration
a. True b. False Indicate whether the statement is true or false
You are traveling quickly along a freeway. Your car has kinetic energy. You suddenly skid to a stop because of congestion in traffic. Where is the kinetic energy that your car once had?
1.All of it goes into internal energy in the road. 2.All of it goes into internal energy in the tires. 3.Some of it goes into internal energy of the road and some into internal energy of the tires. 4.Some of it goes into internal energy of the road, some to internal energy of the tires, some to other internal energy, and some is transferred away by mechanical waves.