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    Velocity of a car in order to meet another car coming towards it

    The spacial equation of car A in the first case: t = Sa/Va t = 44.5/(200/36) The spacial equation of car B in the first case: Sb = - V.t - at^2/2 Being Sb = 220 - 44.5 and T is the value found above in the spacial equation of car A. Acceleration and Speed are negative because the car is moving...
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    Sound Intensity Question

    Homework Statement A choir made up by 100 voices (i.e. 100 singers), during the execution of a song, reaches the sound intensity of 100dB. Assuming that all singers sang with the same intensity, the sound intensity of each singer was...? Homework Equations ΔS=10.log(I/Io) The...
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    Energy conservation problem

    Homework Statement In the image below, there are two balls of mass m attached to a massless rigid metal steam, which can rotate around the point A. Give the necessary velocity to be applied in the lowest ball for the system to reach the horizontal line. Do not consider any system's energy...
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    Increasing a Train's Power

    But I took the velocity of the train as a base, which is constant, not the water's. After all, the power in question is the train's power.
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    Increasing a Train's Power

    I just thought... The force necessary to accelerate the mass of water is F=m.a, and a=V/T (V = 20,0m/s and t=1,0s). So F = 2,0.10³ Energy = Force*Space (Space = 20,0m, because V=20,0m/s and t=1,0s) Energy = 2,0.10³.2,0.10 = 4,0 . 10^4 and finally Power = 40,0kW What mistake I did in the other...
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    Increasing a Train's Power

    Thanks, So the KE = 20kJ and the Power = 20kW. However, the answer on the textbook is 40kW. What am I doing wrong?
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    Increasing a Train's Power

    Homework Statement A train is traveling on a horizontal and straight track, with a constant speed of 20m/s, when it begins to rain. The rain is rigorously vertical and the mass of the water that falls over the train and after that runs vertically by it sides is 100kg per second. Consider the...
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    Two Blocks and a Wheel

    In relation to the acceleration of the wheel, a = -b. So, to an outside observer, a - γ = - (b - γ) Giving γ=(a+b)/2 Right? :)
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    Two Blocks and a Wheel

    Thanks, TSny, I think I got it! Let: M = 2, m = 1, F = 30, g = 10. T - M.g = 2,0a T - m.g = 1,0b F = 2T Then a = -2,50 b = 5,0 Finally: γ=(a+b)/2 γ=1,25m/s² Right?
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    Two Blocks and a Wheel

    @PeterO If I understood you, than the system should be F - (M.g + m.g) = L.a Being L the mass of the wheel, but as the wheel has no mass and putting the values I wrote in the above post, 30 - 30 = 0.a, which keeps me in the dark.
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    Two Blocks and a Wheel

    Hello, Thank you for your answers, but I'm still a little confused. Just to clear out the things: I) The Wheel is massless. II) M=2,0kg, m=1,0kg, F=30,0N. III) The correct answer given in the textbook is γ=1,250m/s² Can someone please show me the calculation for this? Also, this...
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    Two Blocks and a Wheel

    Homework Statement (Sorry if I used any wrong term, English isn't my first language) Be A (mass M) and B (mass m) two blocks connected to each other through an ideal wire passing through a wheel (caster), each block stays at one of the side of the wheel. If we apply a force F pointing up into...
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