Master Physics with Fun Quizzes & Brain Teasers!

what is commutation? how can a commutator convert ac voltages on a machines armature to dc voltages at its terminals?
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what is the highest possible oxidation state for cobalt? A. 6 B. 7C. 4D. 5E. 3
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one hundred joules of heat is added to a system that performs 60 joules of work. the internal energy change of the system is group of answer choicesA. 0 j. B. 40 j. C. 60 j.D. 100 j.
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a public address system puts out 9.47 w of power. what will be the intensity at a distance that results in a surface area of 5.92 m^2?
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if 0.795 mol of ammonia gas occupies 24.5 l at 0.853 atm, what is the celsius temperature? (r = 0.0821 atml/molk)
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3. two scattering mechanisms exist in a semiconductor. if only the first mechanism is present, the mobility will be 250 cm2 /v-s. if only the second mechanism is present, the mobility will be 500 cm2 /v-s. determine the mobility when both scattering mechanisms exist at the same time.
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a ball is traveling at a constant speed of 2 m/s in a circle with a radius of 0.4 m. what is the magnitude of the centripetal acceleration of the ball?
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A magnetic field that is decreasing with time is directed out of the page and passes through a circular loop of wire in the plane of the page. Which of the following is true of the induced current in the wire loop? 1. It is counterclockwise in direction. 2. It is zero in magnitude. 3. It is clockwise in direction. 4. It is directed into the page. 5. It is directed out of the page.
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A bar 10 m long is pivoted at its center. A 20 N weight is hung from one end and a 30 N weight from the other end. At what distance from the fulcrum must a 25 N weight be placed to balance the bar?
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a commuter backs her car out of her garage with a constant acceleration of 1.60 m/s2. (for each answer, enter a number.) (a) how long in seconds does it take her to reach a speed of 2.40 m/s?
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when an rl circuit is connected to a battery, what happens to the potential difference across the resistor and the emf across the inductor?
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why does sunlight appear ornage or red near sunset or sunrise? explain
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64. what is the longest wavelength of radiation that can eject a photoelectron from potassium, given the work function of potassium 2.24 ev? is it in the visible range?
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if the radius of the fillet weld connecting the shafts is r=13.2mm , and the allowable shear stress for the material is allow=159mpa , determine the maximum power the shaft can transmit.
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a cone-shaped cup is made from a circular piece of paper of radius 10 by cutting out a sector and joining the edges ac and bc. find the maximum capacity (volume) of such a cup
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Find the amount of energy transferred to the 4He4He, also called an particle. Assume the reactants are initially at rest. Use the following atomic mass values when determining the total energy released:neutron1.008665u1.008665uhelium-33.016029u3.016029uhelium-44.002603u4.002603uYou will need to use conservation of momentum principle to solve this problem. It will be useful to use the mass of the particle in the form 3727MeV/c23727MeV/c2 for some parts of the problem.
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A block is sliding down an incline from a vertical height "H". A ball rolling down the same incline. The moment of inertia of the ball is 2/5 mR2A. Write the equation which will allow you to find the speed of the block at the bottom of the incline.B. Write the equation which will allow you to find the speed of the ball at the bottom on the incline.C. Which of the objects, either the ball or the block, will have the larger speed at the bottom of the incline? Explain.
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A 3.00-L tank contains air at 3.00atm and 20.0 C. The tank is sealed and cooled until the pressure is 1.00atm.(A)What is the temperature then in degrees Celsius? Assume that the volume of the tank is constant.(B)If the temperature is kept at the value found in part A and the gas is compressed, what is the volume when the pressure again becomes 3.00atm?
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what is the rectifier mean output voltage as a function of the signal generator peak voltage?
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two every day maneuvers that are associated with very high accident rates include - a. backing up - driving in reverse b. using your turn signal improperly
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compute the downward acceleration of a falling wheel of the same shape and size as the one in the laboratory, but made of a different material which is three times as heavy.
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suppose that a cannonball is shot at some speed from the ground at a certain angle from the horizontal. assuming there is no friction, show that the optimal angle to maximize the distance is 45 degrees. to do this, do a picture. decompose the velocity vector into horizontal and vertical components (in terms of the sine and cosine of and the speed ). then consider the horizontal and vertical positions of the ball separately. for the horizontal position, find the distance traveled in time with constant speed. for the vertical, you need to consider the initial speed and the acceleration of gravity, as in section 4.9.
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What is the difference between relative dating and chronometric dating?
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a photon emitted by an excited atom has an energy of 5 ev. what is its frequency?
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