Ch3-HW1-solutions - louey (cal2859) Ch3-HW1 florin (56930)...

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Unformatted text preview: louey (cal2859) Ch3-HW1 florin (56930) 1 This print-out should have 23 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. Problem @22: calculate the difference in the magnitudes of the fields, not the forces. 001 (part 1 of 4) 10.0 points Each part of this problem will state an ex- ample of objects interacting via some force. Choose the fundamental interaction that is responsible in each case. A neutron outside a nucleus decays into a proton, electron, and antineutrino. 1. Gravitational 2. Strong 3. Weak correct 4. Electromagnetic Explanation: Notice the presence of an antineutrino in this decay. Neutrinos (and their antiparticle partners) only interact via the weak force, so this must be a weak interaction. 002 (part 2 of 4) 10.0 points Protons and neutrons attract each other in a nucleus. 1. Weak 2. Strong correct 3. Electromagnetic 4. Gravitational Explanation: The force that holds the nucleus together must be strong enough to overcome the repul- sion between protons due to the electromag- netic force. This is a strong interaction. 003 (part 3 of 4) 10.0 points The Earth pulls on the Moon. 1. Strong 2. Weak 3. Gravitational correct 4. Electromagnetic Explanation: This is a gravitational interaction, in which massive bodies attract each other. 004 (part 4 of 4) 10.0 points Protons in a nucleus repel each other. 1. Electromagnetic correct 2. Gravitational 3. Weak 4. Strong Explanation: This is an example of an electromagnetic in- teraction, in which particles with like charges repel. 005 (part 1 of 2) 10.0 points The mass of the Sun is 2 10 30 kg, and the mass of Mercury is 3 . 3 10 23 kg. The distance from the Sun to Mercury is 4 . 8 10 10 m. First, calculate the magnitude of the gravi- tational force exerted by the Sun on Mercury. Use G = 6 . 67 10- 11 m 3 kg s 2 . Correct answer: 1 . 91068 10 22 N. Explanation: The magnitude of the gravitational force between two objects is given by vextendsingle vextendsingle vextendsingle vector F gr vextendsingle vextendsingle vextendsingle = vextendsingle vextendsingle vextendsingle vextendsingle Gm 1 m 2 r 2 vextendsingle vextendsingle vextendsingle vextendsingle = Gm 1 m 2 r 2 . We just need to plug in the given constants to find the answer: vextendsingle vextendsingle vextendsingle vector F gr vextendsingle vextendsingle vextendsingle = Gm 1 m 2 r 2 louey (cal2859) Ch3-HW1 florin (56930) 2 = ( G )(2 10 30 kg)(3 . 3 10 23 kg) (4 . 8 10 10 m) 2 = 1 . 91068 10 22 N . where G = 6 . 67 10- 11 m 3 kg s 2 . 006 (part 2 of 2) 10.0 points Calculate the magnitude of the gravitational force exerted by Mercury on the Sun....
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This note was uploaded on 03/20/2012 for the course PHY 303K taught by Professor Turner during the Spring '08 term at University of Texas at Austin.

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Ch3-HW1-solutions - louey (cal2859) Ch3-HW1 florin (56930)...

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