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Unformatted text preview: Felder, Jacob – Homework 2 – Due: Sep 19 2006, noon – Inst: Vitaly 1 This print-out should have 7 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. The due time is Central time. 001 (part 1 of 1) 20 points Forces between two objects which are in- versely proportional to the square of the dis- tance between the objects include which of the following? I) Gravitational force between two celestial bodies II) Electrostatic force between two electrons III) Nuclear force between two neutrons. 1. I only 2. I and II only correct 3. I, II, and III 4. III only 5. II and III only Explanation: I) Gravitational force ∝ 1 r 2 . II) Electrostatic force ∝ 1 r 2 . III) The nuclear force is very strong com- pared to the gravitational force and electro- static force over a very short range; outside of that range, however, it is negligible and cannot be proportional to 1 r 2 keywords: 002 (part 1 of 1) 20 points Two identical small charged spheres hang in equilibrium with equal masses as shown in the figure. The length of the strings are equal and the angle (shown in the figure) with the vertical is identical. The acceleration of gravity is 9 . 8 m / s 2 and the value of Coulomb’s constant is 8 . 98755 × 10 9 Nm 2 / C 2 . . 1 7 m 5 ◦ . 03 kg . 03 kg Find the magnitude of the charge on each sphere. Correct answer: 5 . 01307 × 10- 8 C. Explanation: Let : L = 0 . 17 m , m = 0 . 03 kg , and θ = 5 ◦ . L a θ m m q q From the right triangle in the figure above, we see that sin θ = a L ....
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This note was uploaded on 04/03/2009 for the course PHYS 121 taught by Professor Opyrchal during the Fall '08 term at NJIT.
- Fall '08