Two infinite planar sheets are placed parallel to each other. One sheet is uniformly charged with +10 nC/cm^2 and the other with -20nC/cm^2.
A point charge of -5 nC is placed
a) between the sheets
b) in the outside regions.
For each case calculate the strength and show the direction of the
electric force experienced by the point charge.
In: Physics
Pool players often pride themselves on their ability to impart a large speed to a pool ball. In the sport of billiards, event organizers often remove one of the rails on a pool table to allow players to measure the speed of their break shots (the opening shot of a game in which the player strikes a ball with his pool cue). With the rail removed, a ball can fly off the table. As the only participant with a physics background, they have placed you in charge of determining the speed of the players\' break shots.
In: Physics
S = 1/(?0) E X B
How was the poynting vector derived? Please give a detailed derivation of equations that leads to the Poynting Vector.
In: Physics
Using both math and physics to explain
(a) What is the contrast?
(b) On a clear sky, why you can’t see forever?
© When the aircraft parks on the snow surface, sometime it is hard to know that it is in the air or
on the surface, why?
(d) Why we can see a light very far away during night, but not during daytime?
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In: Physics
In a model AC generator, a 497 turn rectangular coil 14.0 cm by 23 cm rotates at 115 rev/min in a uniform magnetic field of 0.58 T.
(a) What is the maximum emf induced in the coil?
V
(b) What is the instantaneous value of the emf in the coil at
t = (?/39) s? Assume that the emf is zero at
t = 0.
V
(c) What is the smallest value of t for which the emf will
have its maximum value?
s
In: Physics
A boy pushes his little sister in a sled across the horizontal ground. He pushes down and to the right on the sled at an angle of 35 degrees from the horizontal. The mass of the sled and the sister together is 60 kg. The coefficient of static friction of the sled with the ground is 0.3 and the coefficient of kinetic friction is 0.2. a) Draw a sketch of the situation and a force diagram of the sled, labeling all forces clearly. b) With what force does the boy have to push to start the sled moving from rest? c) If he continues to push with this force after the sled is moving, what will be the sled's acceleration? d) How long will he have to push the sled with this force unitil the it is moving at 2 m/s? e) Discuss whether or not your answers to parts b through d pass the "common sense" test. Be specific about why you think the answers do or do not make sense.
In: Physics
Rolling Friction questions.
A- How can I quantitatively test Newtons 2nd law for a ball rolling down a wooden ramp using
Ball, wooden ramp, motion sensor, Logger Pro software, computer, meter stick, stopwatch, digital balance, spring scale?
B- How can I determine the coefficient of rolling fiction between the ball and wooden ramp if I lay the ramp flat (no tilt) using the same equipment?
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A silver wire with resistivity 1.59 x 10^-8 ? x m carries a current density of 4.0 mm^2. What is the magnitude of the electric field inside the wire?
A) 0.064 V/m
B) 2.5 V/m
C) 0.040 V/m
D) 0.10 V/m
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design an experiment to measure the effects of chromatic aberration? Just a simple procedure, thanks.
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A 778 kg satellite is in a circular orbit about the Earth at a height above the Earth equal to the Earth's mean radius.
(a) Find the satellite's orbital speed.
(b) Find the period of its revolution.
(c) Find the gravitational force acting on it.
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Two converging lenses, each of focal length 14.9 cm, are placed 39.4 cm apart, and an object is placed 30.0 cm in front of the first lens. Where is the final image formed?
The image is located cm in front of the second lens.
What is the magnification of the system?
M = ?
In: Physics
In: Physics
Consider a combustion plant which uses solid biomass directly in a boiler that is operating a rankine cycle steam plant operates at 30% efficiency to generate electricity. At full operating capacity, the plant can process 2 million hectares of crops annually. Determine the annual electricity output (MWh) for this plant for two of the following crops: Wheat, Miscanthus, Switchgrass, Corn, and/or Hybrid Poplar. Consider (look-up) the energy content (HHV) and crop yields for different biomass types.
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Bob has just finished climbing a sheer cliff above a beach, and wants to figure out how high he climbed. All he has to use, however, is a baseball, a stopwatch, and a friend on the ground below with a long measuring tape. Bob is a pitcher, and knows that the fastest he can throw the ball is about 33.7 m/s. Bob starts the stopwatch as he throws the ball (with no way to measure the ball\'s initial trajectory), and watches carefully. The ball rises and then falls, and after 0.910 seconds the ball is once again level with Bob. Bob can\'t see well enough to time when the ball hits the ground. Bob\'s friend then measures that the ball landed 125 m from the base of the cliff. How high up is Bob, if the ball started from exactly 2 m above the edge of the cliff?
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