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

length= 3.7 ft.

Step-by-step 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.

rick has $1400 and sally has $1500

step-by-step explanation:

to find amount of money rick has after 10 years :

principal = $1000 , time = 10 years , rate = 4% annually

to find amount of money sally has after 10 years :

her friend gives to pay her $50 per year, therefore money she has after 10 years = 50 × 10 = $500

also, sally gets $1000 after 10 years,

therefore, total amount of money sally has after 10 years = 500 + 1000 = $1500

so, after 10 years : rick has $1400 and sally has $1500

it would take 7/10 of an hour too fill the pool.

step-by-step explanation: