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KVPY Sample Paper KVPY Stream-SX Model Paper-18

  • question_answer
    An object is dropped and accelerates downwards. As it falls it is affected by air friction, but never readies terminal velocity during the course of its fall. The graph that could indicate the magnitude of the object's acceleration as a function of time is:

    A)

    B)

    C)

    D)

    Correct Answer: D

    Solution :

    The falling object, when released from rest, has an initial acceleration of \[9.8\,\,m/{{s}^{2}}\](if near the surface of the earth). As its velocity increases, it collides with air molecules at an increasing rate, thus reducing the rate at which it accelerates. (the acceleration is usually modeled as a function of v or \[{{v}^{2}}.\]depending on a number of factors.) The acceleration continuous to decrease until the acceleration of the object is 0, at which point the velocity of the falling object remains constant. The only graph consistent with this analysis is d, where the acceleration curve can be seen to be approaching zero asymptotically.


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