Recent content by Phys student

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    Acceleration, Uniform Ball on Incline

    So in the end we have: K=\frac{1}{2}m\dot{ξ}^2(\sin^2{θ}+\cos^2{θ}(1-\frac{m}{M})^2)+\frac{2}{10}m\dot{ξ}^2 +\frac{m^2\cos^2{θ}\dot{ξ}^2}{2M} V=-mgξ\sin(θ) \dot{E}=m\ddot{ξ}(\sin^2{θ}+\cos^2{θ}(1-\frac{m}{M})^2)+\frac{4}{10}m\ddot{ξ}+\frac{m^2\cos^2{θ}\ddot{ξ}}{M}-mg\sin{θ}=0 When we solve...
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    Acceleration, Uniform Ball on Incline

    What about the rotational kinetic energy? What v do you use?
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    Acceleration, Uniform Ball on Incline

    The x component of the ball's velocity with respect to the ground is: v_x= \dot{ξ}\cos{θ}-\dot{η}=\dot{ξ}\cos{θ}(1-\frac{m}{M}) And the y component is: v_y =\dot{ξ}\sin{θ} Right?
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    Acceleration, Uniform Ball on Incline

    Is the kinetic energy of the ball the sum of the kinetic energies of both coordinates? (ball moving with respect to the incline and the ground) \frac{1}{2}m\dotξ^2 +\frac{1}{2}m\dotη^2
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    Acceleration, Uniform Ball on Incline

    So the expression should have been: \frac{1}{2}m({{\vec{\dotξ}}}+{{\vec{\dotη}}})^2 ?
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    Acceleration, Uniform Ball on Incline

    It is along the slope, How did the kinetic energy expression make you assume it's relative to the ground?
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    Acceleration, Uniform Ball on Incline

    Homework Statement [/B] A uniform solid ball of mass m rolls without slipping down a right angled wedge of mass M and angle θ from the horizontal, which itself can slide without friction on a horizontal floor. Find the acceleration of the ball relative to the wedge. 2. The attempt at a...
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    Maxima and Minima, Rod Rotating on a Surface With Friction

    I see what you mean now. If we substitute x= \frac{L}{2} we get: T_m = \frac{Mω}{3gλμ} Now, when we substitute x=0 or x=L we get: T_M = \frac{2Mω}{3gλμ} So: \frac{T_m}{T_M} = \frac{1}{2} Can this result be derived intuitively, without calculus? Anyway, thank you very much...
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    Maxima and Minima, Rod Rotating on a Surface With Friction

    WolframAlpha link for derivative: http://goo.gl/M7Psfe I guess it could be possible that there's only one extremum but it would mean that we don't have both a maximum and minimum time.
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    Maxima and Minima, Rod Rotating on a Surface With Friction

    We have: α=\frac{μgλ(L^2 +2(x^2-Lx))}{\frac{1}{6}ML^2 +2M(\frac{L}{2} -x)^2} T= \frac{ω}{α} = \frac{ω(\frac{1}{6}ML^2 +2M(\frac{L}{2} -x)^2)}{μgλ(L^2 +2(x^2-Lx))} When we take the derivative we get: \frac{d}{dx} \frac{ω(\frac{1}{6}ML^2 +2M(\frac{L}{2} -x)^2)}{μgλ(L^2 +2(x^2-Lx))} =...
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    Maxima and Minima, Rod Rotating on a Surface With Friction

    I used the parallel axis theorem. But I think I made a mistake, because the theorem applies to the moment of inertia around the center of mass so it should have been: I=\frac{1}{12}ML^2 +M(\frac{L}{2} -x)^2
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    Maxima and Minima, Rod Rotating on a Surface With Friction

    Homework Statement A uniform rod of mass M and length L can rotate around point P which is at position x from one end of the rod as shown in the figure. The rod is gently placed on a rough horizontal surface that has a friction coefficient μ. and at t=0 starts rotating with angular velocity...
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    Centripetal Acceleration of car

    You want to find a relation between the velocity of car A and car B, and you're given a relation between the radii of their circular paths and a relation between their centripetal accelerations. Try to write down some equations.
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    Finding maximal total current for a system

    So the answer is 1.7A because after changing to fuse C a larger maximal current is possible where fuse A would burn and the current (1.7A) would be redirected to fuse C only.
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    Finding maximal total current for a system

    Then fuse A would burn and the current would be redirected to fuse C only?
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