To develop this problem it is necessary to apply the oscillation frequency-related concepts specifically in string or pipe close at both ends or open at both ends.
By definition the oscillation frequency is defined as

Where
v = speed of sound
L = Length of the pipe
n = any integer which represent the number of repetition of the spectrum (n)1,2,3...)(Number of harmonic)
Re-arrange to find L,

The radius between the two frequencies would be 4 to 5,


Therefore the frequencies are in the ratio of natural numbers. That is

Here f represents the fundamental frequency.
Now using the expression to calculate the Length we have

Therefore the length of the pipe is 1.3m
For the second harmonic n=2, then

Therefore the length of the pipe in the second harmonic is 2.6m
Answer:
because our some of the energy goes from our eyes
explanation;
There are several reasons why it's important to close our eyes while we sleep. Closed eyelids block light, which stimulates the brain to wakefulness. Closing our eyes also protects and lubricates the eyes while we sleep
Work is force times distance, so W = 40 N * 10 m = 400 J
Answer:
(a) 0.115 m
(b) 2.08 x 10^-5 J
Explanation:
mass of bob, m = 81 g = 0.081 kg
The equation of oscillation is given by
θ = 0.068 Cos {9.2 t + Ф}
Now by comparison
The angular velocity
ω = 9.2 rad/s
(a) 
where, L be the length of the pendulum


L = 0.115 m
(b) A = L Sinθ
A = 0.115 x Sin 0.068
A = 7.8 x 10^-3 m
Maximum kinetic energy
K = 0.5 x mω²A²
K = 0.5 x 0.081 x 9.2 x 9.2 x 7.8 x 7.8 x 10^-6
K = 2.08 x 10^-5 J