Question

The time of a pendulum varies as the square root of its length. If the length if a pendulum which beats 15seconds is 9cm, find the length that beats 80seconds and the time of a pendulum with length 36cm

Answer 1

length= 3.7 ft.

Explanation:

T= (square root of length) * k

1.8 seconds = (square root of 3) * k

k= 1.8 seconds / (square root of 3)

a.) T= (square root of 11) k

substituting k:

T=(square root of 11) * 1.8 seconds / (square of 3)

T= 3.4 seconds

b.) 2 seconds = (square root of length) k

substituting k:

2 seconds =(square root of length) 1.8 seconds / (square root of 3)

Divide the equation by 1.8 seconds / (square root of 3):

2 seconds / [1.8 seconds / (square root of 3)] = (square root of length)

10(square root of 3) / 9 = (square root of length)

square both sides:

100/7 ft= length

length= 3.7 ft.

Hope this helps.