A mass that weight stretches a spring . The system is acted on by an external force . If the mass is pushed up and then released, determin

Question

A mass that weight stretches a spring . The system is acted on by an external force . If the mass is pushed up and then released, determine the position of the mass at any time . Use as the acceleration due to gravity. Pay close attention to the units.

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Euphemia 6 months 2021-08-05T21:29:00+00:00 1 Answers 8 views 0

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    2021-08-05T21:30:17+00:00

    Answer:

    x = A cos wt

    Explanation:

    To determine the position we are going to solve Newton’s second law

                 F = m a

               

    Spring complies with Hooke’s law

              F = -k x

    And the acceleration of defined by

              a = d²x / dt²

             

    We substitute

            – k x = m d²x / dt²

             dx² / dt² + k/m  x = 0

    Let’s call

               w² = k / m

    The solution to this type of differential equation is

               x = A cos (wt + Ф)

    Where A is the initial block displacement and the phase angle fi is determined by or some other initial condition.

    In this case the body is released so that at the initial speed it is zero

    From which we derive this expression

             v = dx / dt = a w sin ( wt + Ф)

             

    As the System is released for t = 0 the speed is v = 0

             v = sin Ф = 0

    Therefore Ф = 0

    And the equation of motion is

             x = A cos wt

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