Identical point charges (+30 ?C) are placed at the corners of a rectangle (4.0 m × 6.0 m). How much external energy is required to bring a charge of 55 ?C from infinity to the midpoint of one of the 6.0-m long sides of the rectangle?
a. 22 J
b. 16 J
c. 13 J
d. 19 J
e. 8.0 J
b
You might also like to view...
Thin Lenses: A wrench is placed at 30 cm in front of a diverging lens with a focal length of magnitude 10 cm. What is the magnification of the wrench?
A. 0.25 B. -0.25 C. 0.67 D. -0.67 E. 4.0
In a certain gas the molecules are 5.0 × 10?9 m apart on average, have a mean free path of 5.0×10?6 m, and have an average speed of 500 m/s. The rate at which a molecule has collisions with other molecules is about:
A. 10?11 s?1 B. 10?8 s?1 C. 1 s?1 D. 10^8 s?1 E. 10^11 s?1
Biomagnetism has been detected in
A) bacteria. B) pigeons. C) wasps. D) humans. E) all of the above
Which of the following frames would be an appropriate inertial reference frame for analyzing the effects on the earth of its gravitational interaction with the moon? In each case, answer A if the frame is appropriate, or B if it would be bad for this purpose. Except for the first case, assume the frames are nonrotating.
(a) A frame attached to the earth’s surface (b) A frame attached to the earth’s center of mass (CM) (c) A frame attached to the earth–moon system’s CM (d) A frame attached to the sun’s CM (e) A frame attached to the entire solar system’s CM