What is a joule? What is the equivalent unit in the English system?
In: Physics
Describe magnetic inductance and give examples.
Describe R-L, L-C, and L-R-C series circuits, and give examples.
PLEASE DO NOT WTITE IT BY HAND
.
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A charged paint is spread in a very thin uniform layer over the surface of a plastic sphere of diameter 20.0 cmcm , giving it a charge of -19.0 μCμC .
Part A: Find the electric field just inside the paint layer.
Part B: Find the electric field just outside the paint layer.
Part C: Find the electric field 7.00 cm outside the surface of the paint layer.
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Three 90.790.7 g masses are connected in a triangular shape by massless rigid wires as shown in the first image (which is not drawn to scale). The coordinates of each mass are given in centimeters. Mass A is located at (0,0)(0,0), mass B is at (10.2,19.5)(10.2,19.5), and mass C is at (17.3,13.4)(17.3,13.4). Find the xx- and yy‑coordinates of the center of mass of the triangular object.
Two more 90.790.7 g masses are connected by a straight piece of wire and affixed to the original configuration as shown. The coordinates of mass D are (0,−39.1)(0,−39.1) and the coordinates of mass E are (0,39.1)(0,39.1). Find the xx- and yy‑coordinates of the new center of mass of the combined object.
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A 8.6-kg cube of copper (cCu = 386 J/kg-K) has a temperature of 750 K. It is dropped into a bucket containing 5.1 kg of water (cwater = 4186 J/kg-K) with an initial temperature of 293 K.
1)
What is the final temperature of the water-and-cube system?
K
2)
If the temperature of the copper was instead 1350 K, it would cause the water to boil. How much liquid water (latent heat of vaporization = 2.26 × 106 J/kg) will be left after the water stops boiling?
kg
3)
Let's try this again, but this time add just the minimum amount of water needed to lower the temperature of the copper to 373 K. In other words, we start with the cube of copper at 750 K and we only add enough water at 293 K so that it completely evaporates by the time the copper reaches 373 K. Assume the resulting water vapor remaining at 373 K. How much water do we need ?
kg
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While taking photographs in Death Valley on a day when the
temperature is 50.0°C, Bill Hiker finds that a certain voltage
applied to a iron wire produces a current of 1.000 A. Bill then
travels to Antarctica and applies the same voltage to the same
wire. What current does he register there if the temperature is
-88.0°C? Assume that no change occurs in the wire's shape and
size.
In: Physics
- In your own words, explain potential energy, kinetic energy, conservation of energy and examples in daily life.
- In your own words, explain the definition of work in Physics.
- In your own words, explain Hooke's Law and elastic potential energy.
In: Physics
Assume a cup contains about 12 oz or 340 g of water at room temperature, about 20 degree C. The electric kettle draws energy from the wall outlet at a rate (Power) of 990W. Draw a single Energy-Interaction Diagram for the process of bringing the water to a rolling boil. Choose an appropriate physical system, as well as an initial and a final point in time and indicate all initial and final conditions on your timeline. Explicitly state any other assumptions you're making in words (incl. observations) and include an energy-conservation equation. Use your energy-conservation equation to calculate the amount of energy necessary to bring the water to a rolling boil. Then use what you know about the power of the electric kettle to calculate how long it will take to bring the water to a rolling boil (all water in liquid/gas mixed state).
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A metallic circular plate with radius r is fixed to a tabletop. An identical circular plate supported from above by a cable is fixed in place a distance dd above the first plate. Assume that dd is much smaller than r. The two plates are attached by wires to a battery that supplies voltage V.
1) What is the tension in the cable? Neglect the weight of the plate.
Express your answer in terms of the variables d, r, V, and constants ϵ0, pi.
F=
2)
The upper plate is slowly raised to a new height 2d. Determine the work done by the cable by integrating ∫d to 2d F(z)dz, where F(z) is the cable tension when the plates are separated by a distance z.
Express your answer in terms of the variables d, r, V, and constants ϵ0,pi.
W=
3) Compute the energy stored in the electric field before the top plate was raised.
Express your answer in terms of the variables d, r, V, and constants ϵ0, pi.
U=
4) Compute the energy stored in the electric field after the top plate was raised.
Express your answer in terms of the variables d, r, V, and constants ϵ0, pi.
U=
5)
is the work done by the cable equal to the change in the stored electrical energy? If not, why not?
| The work done in separating the plates is equal to energy change in the plates. |
| The work done in separating the plates is equal to the magnitude of the energy change in the plates. This does not mean that the work done is equal to the change in the energy stored in the plates. The work done on the plates is positive but the plates lose energy. The plates are connected to the battery, so the potential difference across them remains constant as they are separated. Therefore charge is forced off of the plates through the battery, which does work on the battery. |
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An airplane pilot wishes to fly to his destination 500 mi due west, but the wind is blowing at 23.1 mi/hr toward 14.1° north of west. The speed of the plane relative to the air is 166.5 mi/hr. At what angle (south of west) must the pilot orient the plane in order to fly to his destination directly?
If the pilot orients the plane at that angle, what will be the speed of the plane relative to the ground?
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Suppose the electron in a hydrogen atom is modeled as an
electron in a one-dimensional box of length equal to the Bohr
diameter, 2a0. What would be the ground-state
energy of this "atom"?
______________eV
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An object is formed by attaching a uniform, thin rod with a mass of mr = 7.25 kg and length L = 5.56 m to a uniform sphere with mass ms = 36.25 kg and radius R = 1.39 m. Note ms = 5mr and L = 4R.
1)What is the moment of inertia of the object about an axis at the left end of the rod?
3) What is the moment of inertia of the object about an axis at the center of mass of the object? (Note: the center of mass can be calculated to be located at a point halfway between the center of the sphere and the left edge of the sphere?
5) What is the moment of inertia of the object about an axis at the right edge of the sphere?
6)
Compare the three moments of inertia calculated above, from least to greatest (or equal)
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How many inhabitable planets are there in the universe? Two estimates are given by Drake's Equation and Seager's Equation. Do a little research on Drake's Equation and Seagar's Equation. Summarize what you've found. From a probability standpoint, particularly subjective probability, how do these equation hold up?
Comment and justify your comments particularly in the light of subjective probability.
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Find the total energy associated with the earths current rotation and compare this to the gain in the moons orbital energy. What fraction of the energy has been lost as heat?
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The magnetic field perpendicular to a circular wire loop 7.7 cmcm in diameter is changed from +0.44 TT to -0.27 TT in 150 msms , where + means the field points away from an observer and - toward the observer.
Calculate the induced emf.
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