Suppose that a pendulum clock keeps time exactly correctly on Earth. Now suppose that you take this clock to planet X and find that the clock’s hour hand makes α revolutions every hour. Find a formula for the magnitude of the acceleration due to gravity near the surface of planet X. What would α be on the moon?

Respuesta :

Answer:

The gravity at planet X is  [tex]g= 3.05*10^{-6} \alpha^2 m/s^2[/tex]

The value of [tex]\alpha[/tex] on the moon is  [tex]\alpha = 730.38 \ revolutions[/tex]

Explanation:

  From the question we are told that

        The clocks hour hand makes [tex]\alpha[/tex] revolution every 1 hour which is 3600 sec

this implies that the time peroid for 1 revolution would be  [tex]= \frac{3600}{\alpha }sec[/tex]

   The peroid  for a pendulum is mathematically represented as

            [tex]T = 2 \pi\sqrt{\frac{L}{g} }[/tex]

Where L is the pendulum length

            g is the acceleration due to gravity

Let assume that we have a pendulum that counts in second on earth

   This implies that its peroid would be = 2 second

   i.e one second to swimg forward and one second to swing back to its original position

  Now the length of this pendulum on earth is

          [tex]L = \frac{gT^2}{4 \pi^2}[/tex]         [Making L the subject in above equation]

 Substituting values

        [tex]L = \frac{9.8 * (2)^2}{4 * (3.142)^2}[/tex]

           [tex]= 1[/tex]

When the same pendulum is taken to planet X  the peroid would be

                 [tex]T = \frac{3600}{\alpha }[/tex]

Recall this value was obtained above for 1 revolution (from start point to end point back to start point)

      So the acceleration due to gravity on this planet would be mathematically represented as

                [tex]g = \frac{4 \pi L }{T^2}[/tex]   [making g the subject in the above equation]

     substituting values

               [tex]g = \frac{4 * 3.142^2 * 1}{[ \frac{3600}{\alpha } ]^2}[/tex]

                    [tex]g= 3.05*10^{-6} \alpha^2 m/s^2[/tex]

On moon the acceleration due to gravity has a constant value of

     [tex]g = 1.625 m/s^2[/tex]

The period of this pendulum  on the moon can be mathematically evaluated as

      [tex]T = 2\pi \sqrt{\frac{L}{g} }[/tex]

 substituting value

     [tex]T = 2 *3.142 \sqrt{\frac{1}{1.625} }[/tex]

        [tex]= 4.929s[/tex]

 given that  

       [tex]1 \ revolution ----> 4.929s\\ \\ \alpha \ revolution -------> 3600 \ s[/tex]  {Note 1 revolution takes a peroid }

Making [tex]\alpha[/tex] the subject of the formula

           [tex]\alpha =\frac{3600}{4.929}[/tex]

              [tex]\alpha = 730.38 \ revolutions[/tex]