a. Consider a capacitor being charged by a battery in a simple RC circuit. After a switch is thrown to charge the capacitor, when is the battery delivering the most power? It is when immediately after the switch is thrown. Not when the capacitor is fully charged or half charged. Why? Please explain in detail. b. After a switch is thrown to charge the capacitor, the capacitance is constant regardless of if it is fully or half charged or if it is immediately when the switch is thrown. Why? Please explain in detail. After a switch is thrown to charge the capacitor, when is the electric field greatest in the capacitor gap? Once the capacitor is fully charged. Why?
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Two loudspeakers are about 10 m apart in the front of a large classroom. If either speaker plays a pure tone at a single frequency of 400 Hz, the loudness seems pretty even as you wander around the room, and gradually decreases in volume as you move farther from the speaker. If both speakers then play the same tone together, what do you hear as you wander around the room?
| The sound is louder but maintains the same relative spatial pattern of gradually decreasing volume as you move away from the speakers. | |
| The pitch of the sound increases to 800 Hz, and the sound is louder but not twice as loud. It is louder closer to the speakers and gradually decreases as you move away from the speakers−except near the back wall, where a slight echo makes the sound louder. | |
| As you move around the room, some areas seem to be dead spots with very little sound, whereas other spots seem to be louder than with only one speaker. | |
| The sound is twice as loud−so loud that you cannot hear any difference as you move around the room. | |
| At points equidistant from both speakers, the sound is twice as loud. In the rest of the room, the sound is the same as if a single speaker were playing. |
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12. Your friend with great excitement tells you about his newest idea to solve the energy crisis: He wants to use an electromotor to drive a generator and then use part of the electric power generated to power the electromotor while using the rest to power his home. What would you tell him?
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A man on a road trip drives a car at different constant speeds over several legs of the trip. He drives for 50.0 min at 55.0 km/h, 15.0 min at 65.0 km/h, and 45.0 min at 45.0 km/h and spends 20.0 min eating lunch and buying gas.
(a)
What is the total distance traveled over the entire trip (in km)?
(b)
What is the average speed for the entire trip (in km/h)?
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What does a finite length 2D sinusoidal standing wave with one node look like?
What does a finite length 3D sinusoidal standing wave with one node look like
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What are some examples of supersonic wings?
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Double-wedge airfoil |
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Thick cambered airfoils |
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Swept wings |
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All of the above |
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A and C above |
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A 4.70 kg block hangs from a spring with spring constant 2300 N/m . The block is pulled down 5.50 cm from the equilibrium position and given an initial velocity of 1.10 m/s back toward equilibrium.
1) What is the frequency of the motion?
2) What is the amplitude?
3) What is the total mechanical energy of the motion?
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On a frictionless air table, Puck A with mass ?A = 0.120 kg is moving at speed ?A = 2.80 m/s in the +? direction when at the origin it hits Puck B (of mass ?B = 0.140 kg), which is initially at rest. Puck A is deflected in the collision into a final velocity of ?'A = 2.10 m/s at an angle of 30° from the + ? axis. The collision is not elastic.
a) Write down equations expressing conservation of momentum in both the ? and ? directions.
b) Solve the equations for velocity (?'B, ?'B) of Puck B.
c) What fraction of the initial kinetic energy is lost in this collision?
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A 1.08 kg copper rod rests on two horizontal rails 0.84 m apart and carries a current of 60 A from one rail to the other. The coefficient of static friction between rod and rails is 0.53. What is the smallest magnetic field (not necessarily vertical ) that would cause the rod to slide?
A) What is the angle of B from the vertical? (deg)
B) What is the magnitude of B?
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1. Describe location in the universe.
2. Compare and contrast distance, time, and speed.
3. Discuss the speed of light and the theory of special relativity.
4. Discuss inertia and momentum and the difficulties accelerating to speed of light.
5. Compare and contrast Solar Sails, Ion Engines, and Warp Drives - accelerating in space.
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Astronomers estimate that there are between 200 billion to 400 billion stars contained within the Milky Way and Andromeda Galaxy probably has 1 trillion stars. There may be around 500 billion galaxies in the observable universe.
So, my question is, statistically speaking because of the number of stars, there is should be lots of chances of stars going supernova; where at times they glow brighter than a whole galaxy. Why then do we not see many supernovas, for example like the 1987A? Why have we not been able to see one in our own galaxy since the SNR G1. Should there not be more supernovas in surrounding galaxies and even our own one as it has around 400 billion stars.
I appreciate that there are different types of stars and various life span, but our galaxy being almost as old as the universe, surely there should be stars dying all the time.
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3. Resistors and capacitors are not marked with their exact values, but only approximate values with a tolerance. Determine the tolerance marked on the resistors and capacitors you are using. If there is a discrepancy between the two quantities compared in Question 2, can the tolerance values explain the difference?
7.What fraction of the initial potential remains after one time constant has passed? After two time constants? Three?
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A pair of speakers separated by distance d = 0.640 m are driven by the same oscillator at a frequency of 681 Hz. An observer originally positioned at one of the speakers begins to walk along a line perpendicular to the line joining the speakers as in the figure below. (Use v = 343 m/s.) Two speakers are side by side, with one speaker on the left and one on the right. The speakers are separated by a distance d and emit sound waves in the same direction. A man stands directly in front of the speaker on the right but a distance x away from the speaker. (a) How far must the observer walk before reaching a relative maximum in intensity? m (b) How far will the observer be from the speaker when the first relative minimum is detected in the intensity? m
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