Recent content by ash1262

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    Angular momentum and kinetic energy

    The truck (mass M) is moving with velocity v horizontally on Earth (considered an inertial frame) when a stationary mass (m) is lowered (loaded) slowly on it vertically. The mass (m) had zero momentum in the horizontal direction before it was lowered on the truck and zero kinetic energy...
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    Angular momentum and kinetic energy

    In the same lines, a truck moving horizontally with velocity 'v' is loaded with a mass 'm', the mass being lowered vertically. The truck with the mass will move at a lower velocity to conserve the momentum. Again the kinetic energy will drop. Where does the kinetic energy go? I could not detect...
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    Angular momentum and kinetic energy

    Thanks PF Patron. I was trying to calculate the work done by the centripetal force when a stone rotating at the end of a string is brought in from initial radius R to final radius R/2, by integrating [∫mω^2/x^3 r^4 dx] from r to r/2. The magnitude is the same as the gain in kinetic energy, but...
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    Angular momentum and kinetic energy

    Thanks Nugatory. When the boy pulls out his hand again the energy is restored to the previous level. Where does the extra energy go? Friction of the muscles?
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    Angular momentum and kinetic energy

    A boy sitting on a rotating chair (ignore friction) with his hands stretched outwards, pulls in his hands thus reducing the moment of inertia of the chair-boy system. The angular velocity will increase to conserve the angular momentum. The kinetic energy of the system will also increase (as...
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    Free cylinder on an accelerating platform

    Thanks for the encouragement.
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    Free cylinder on an accelerating platform

    Thanks Bruce, your reply was very useful. The solution I had used a pseudo force to derive the acceleration, and I could not visualize what was really happening. Now I have derived the acceleration without using the pseudo force, and can visualize the motion!
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    Free cylinder on an accelerating platform

    The solution says that the linear acceleration of the cylinder is 3/2 times acceleration of the platform, which I can't visualize. I feel it should be same as that of the platform as there is no slipping (the surface is rough). Again, the cylinder rolls in the opposite direction of the...
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    Free cylinder on an accelerating platform

    Suppose a cylinder is resting on a horizontal platform on plane x-y with its axis parallel to the y axis, and the platform accelerates in the x direction. Assume that the axis remains parallel to the y-axis and the surface is rough. What is the motion (acceleration:linear as well as rotational)...
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    Static friction in body with no intention to move

    Dear DaleSpam, Does that mean that we can not assume that the static friction will be at the limiting value? Thus, as the friction can take any value, the reaction from the wall is indeterminate? Can we not rig up an experiment using different surfaces with different coefficients of friction...
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    Static friction in body with no intention to move

    Thanks, UltrafastPED and Drakkith. In the case of the block, since the limiting value of the static friction is 5*10*0.2=10N, the reaction from the wall should be 190N. I wonder if someone in the forum can conduct an experiment to confirm/demonstrate this phenomenon.
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    Static friction in body with no intention to move

    Suppose a block of mass 5 kg is resting on a horizontal surface and coefficient of static friction between block and surface is 0.2. If the block is pushed against a vertical wall with a force of 200 N, will the static friction oppose the force? The body has no intention of moving as it is...
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