Parallel-Plate Capacitor: A tiny 0.0250-µg oil drop containing 15 excess electrons is suspended between two horizontally closely-spaced metal plates that carry equal but opposite charges on their facing surfaces. The plates are both circular with a radius of 6.50 cm. (k = 1/4??0 = 9.0 × 109 N ? m2/C2, e = 1.6 × 10-19 C)(a) How much excess charge must be on each plate to hold the oil drop steady?(b) Which plate must be positive, the upper one or the lower one?
What will be an ideal response?
(a) 12.0 µC (b) upper plate
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When a one-megaton nuclear bomb is exploded, approximately 4.0 × 10^15 J of energy is released. How much mass would this represent in a mass-to-energy conversion? (c = 3.00 × 10^8 m/s)
a. 1.333 × 10^6 kg b. 0.044 kg c. 0.444 kg d. 3.600 kg e. 4.0 × 10^3 kg
What nuclear fusion mechanism does an isolated white dwarf use to generate energy?
a. proton-proton chain b. CNO cycle c. triple alpha process d. white dwarfs don't generate their own energy.
The figure shows a pV diagram of a gas for a complete cycle. During part bc of the cycle, 1190 J of heat flows into a system, and at the same time the system expands against a constant external pressure of 7.00 × 104 Pa as its volume increases from 0.0200 m3 to 0.0800 m3. Calculate the change in internal (thermal) energy of the system during part bc of the cycle. If the change is nonzero, be sure to indicate whether the change is positive or negative.
Work: You carry a 7.0-kg bag of groceries 1.2 m above the ground at constant speed across a 2.7 m room. How much work do you do on the bag in the process?
A. 0.00 J B. 82 J C. 185 J D. 157 J