13) a pendulum of mass m, length l, amplitude a, and on the earth with acceleration due to gravity of g has a period t. how long would the pendulum need to be in order to to have a period of 2t?

4L

Explanation:

mass of pendulum = M, length of pendulum, L1 = L,

acceleration due to gravity = g, Amplitude = A

Use the formula for the time period for simple pendulum

    ..... (11)

Let the new length be L2 for which the time period is 2T.

         ..... (2)

Divide equation (2) by equation (1)

So, L2 = 4 L

Thus, the length of the pendulum is 4 L.

the answer is c. the lower legs are levers, and the knees are fulcrums. the ankles hold the loads.