Charge in an Electric Field: A small styrofoam ball of mass 0.120 g is placed in an electric field of 6000 N/C pointing downward. What excess charge must be placed on the ball for it to remain suspended in the field?
A. -16.0 nC
B. -18.0 nC
C. -57.2 nC
D. -125 nC
E. -196 nC
Answer: E
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Two current-carrying wires are parallel to one another and separated by 1 cm. If the distance between them is increased to 2 cm the new force will be what factor times the original force?
A. ½ B. 4 C. 2 D. 1 E. ¼
An initially uncharged hollow metallic sphere with radius of 5 cm has a small object with a charge of +15 µC carefully placed at the center of the sphere through a hole in the latter's surface. What charge resides inner surface of the sphere?
a. –2 000 µC b. –15 µC c. +15 µC d. zero e. +2 000
The circumference of a bicycle wheel is 2 meters. If it rotates at 1 revolution per second then its linear speed is
A) 1 m/s. B) 2 m/s. C) 3 m/s. D) 3.14 m/s. E) 6.28 m/s.
A grinding wheel is spinning at a rate of 20.0 revolutions per second. When the power to the grinder is turned off, the grinding wheel slows with constant angular acceleration and takes 80.0 s to come to a rest
(a) What was the angular acceleration of the grinding wheel as it came to rest? (b) How many rotations did the wheel make during the time it was coming to rest?