Physics

What was Gan De's contribution to astronomy?A.He developed the world's first star catalogue.B.He was the first to record a lunar eclipse.C.He was the first to observe planets.D.He invented the telescope.
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two point charges 2.0 cm apart have an electric potential energy -180 j . the total charge is 0 nc .
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the velocity of a train is 80.0 km/h, due west. one and a half hours later its velocity is 65.0 km/h, due west. what is the train's average acceleration?
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A 2.0 cm tall object is placed 25 cm in front of a converging lens. The image is found 64 cm on the other side of the lens.The focal length of the lens is ________.0.011 cm0.024 cm41 cm0.056 cm18 cm15 cm
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A mass on a spring in SHM has amplitude A and period T. Part A At what point in the motion is the velocity zero and the acceleration zero simultaneously? x > 0 x = A x < 0 x = 0 None of the above.
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what is the frequency of a photon that has the same momentum as a neutron moving with a speed of 1300 m/s ?
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which populatia food worker take the temp of hot held pasta in several place are above the temp dannger zone but some ares of the pasta are colder then other what should you do"
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19. which formula may be used for the momentum of all particles, with or without mass?
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use heisenberg uncertainty principle to determine minimum uncertainty in position for a proton with a velocity of 5000m/s
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A mass connected to a light string oscillates in simple harmonic motion. The work done by air friction affects (Select all that apply)Athe mechanical energy of the mass.Bthe kinetic energy of the mass.Cthe potential energy of the mass.Dthe thermal energy of the entire system.
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how does loudness relate to the unit decibel? how does loudness relate to the unit decibel? the decibel is a unit of measurement of sound frequency. perceived loudness is determined by sound frequency and sound wavelength. the decibel is a unit of measurement of sound intensity. perceived loudness is determined completely by sound intensity. the decibel is a unit of measurement of sound intensity. perceived loudness depends on sound intensity and sound frequency. the decibel is a unit of measurement of sound frequency. perceived loudness depends on sound intensity and sound frequency.
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a 1cm tall candle flame is 60cm from a lens with a focal length of 20cm. what are the image distance and hte height of the flame's image?
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a - dc lightbulb dissipates of power. if 3 bulbs are used in the lighting of a certain popup camper, which of the following fuses would you expect to find protecting the lighting system? you may assume that when switching on any of the 3 lights, the bulb draws momentarily % more current than its usual dc current draw
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Disk a has a mass of 6 kg and an initial angular velocity of 360 rpm clockwise; disk b has a mass of 3 kg and is initially at rest. the disks are brought together by applying a horizontal force of magnitude 20 n to the axle of disk a. knowing that k = 0.15 between the disks and neglecting bearing friction, determine (a) the angular acceleration of each disk, (b) the final angular velocity of each disk
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Please answer in complete sentences and answer all parts. Thank you very muchPart 2 of the problem will be out next.
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1. A student sets up an experiment with a cart on a level horizontal track. The cart is attached with an elastic cord to a force sensor that is fixed in place on the left end of the track. A motion sensor is at the right end of the track, as shown in the figure above. The cart is given an initial speed of vo = 2.0 m/s and moves with this constant speed until the elastic cord exerts a force on the cart. The motion of the cart is measured with the motion detector, and the force the elastic cord exerts on the cart is measured with the force sensor. Both sensors are set up so that the positive direction is to the left. The data recorded by both sensors are shown in the graphs of velocity as a function of time and force as a function of time below. (a) Calculate the mass m of the cart. For time period from 0.50 s to 0.75 s, the force F the elastic cord exerts on the cart is given as a function of timer by the equation F = Asin(or), where A = 6.3 N and a 12.6 rad/s. (b) Using the given equation, show that the area under the graph above is 1.0 Ns
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Kari walks 10m up the stairs. Sandra runs up the same flight of stairs. What is true about the amount of work each did?Group of answer choicesKari did more workthe amount of work is the sameSandra did more workI cannot determine an answer from the information given
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Comment on energy conservation in this diagram.
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the mysterious sliding stones. along with the remote racetrack playa in death valley, california, stones sometimes gouge out prominent trails in the desert floor, as if the stones had been migrating (fig.). for years curiosity mounted about why the stones moved. one explanation was that strong winds during occasional rainstorms would drag the rough stones over the ground softened by rain. when the desert dried out, the trails behind the stones were hard-baked in place. according to measurements, the coefficient of kinetic friction between the stones and the wet playa ground is about 0.80. what horizontal force must act on a 20 kg stone (a typical mass) to maintain the stones motion once a gust has started it moving?
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A 2000 N force stretches a wire by 1.0mm.a) A second wire of the same material is twice as long and has twice the diameter. How much force is needed to stretch it by 1.0mm?b) A third wire of the same material is twice as long as the first and has the same diameter. How far is it stretched by a 4000 N force?
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if the heat capacity of the calorimeter is 37.90 kjk1,37.90 kjk1, how many nutritional calories are there per gram of the candy?
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An amusement park ride consists of a large vertical cylinder that spins about its axis fast enough that any person inside is held up against the wall when the floor drops away. What is the minimum angular velocity w_min needed to keep the person from slipping downward? The acceleration due to gravity is 9.8 m/s^2, the coefficient of static friction between the person and the wall is 0.78, and the radius of the cylinder is 6.82 m. Answer in units of rad/s. Please show work.
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How much gold already at its melting point would melt if 6000 Joules of thermal energy were used to heat it?For gold the specific latent heat of fusion is 120 000 J/kg and the specific latent heat of vaporisation is 64 000 J/kg.ASAP please the assignment is due tonight.
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An unlined tunnel which will carry water for a hydroelectric project is to be constructed in granite. The maximum water pressure acting on the granite is estimated to be 10MPa. The modulus of elasticity of the granite is measured to be 3.4 x 104 MPa: 1) How much will 3 m of rock around the tunnel be strained by the force of the water? ii) If the weight of the rock is 25.9 kN/m' and the tunnel is overlain by 20 m of rock, what is the rock stress in KN m acting on the top of the tunnel
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