Energy Density: At a particular point and instant, the magnetic field component of an electromagnetic wave is 15.0 ?T. What is the magnetic energy density of this wave at that point and instant? (c = 3.00 × 108 m/s, ?0 = 4? × 10-7 T ? m/A, ?0 = 8.85 × 10-12 C2/N ? m2)
A. 2.26 × 10-4 J/m3
B. 8.95 × 10-5 J/m3
C. 1.79 × 10-4 J/m3
D. 4.47 × 10-4 J/m3
E. 9.72 × 10-5 J/m3
Answer: B
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In Figure 6-2 the scale at left is attached to the ceiling and a mass of 1.00 kg hangs from it. It reads 9.81 N. The identical scale at the right is connected by perfect strings passing over perfect pulleys to two 1.00 kg masses hanging vertically at the end of the strings. The scale at right reads
A. exactly 9.81 N.
B. less than 9.81 N
D. more than 9.81 N,
E. more than 19.62 N
As you go higher and higher above the surface of the Earth, the weight of a body __________
Fill in the blank(s) with correct word
A 1200-kg car moving at 15.6 m/s suddenly collides with a stationary car of mass 1500kg. If the two vehicles lock together, what is their combined velocity immediately after the collision?
A) 12.1 m/s B) 8.6 m/s C) 6.9 m/s D) 5.5 m/s
The total kinetic plus potential energy of a body
a. can be negative b. always stays constant if the body is freely falling c. always stays constant if friction is acting d. can remain constant even if the body's speed is decreasing