I think it is when shot scrapes off the top of the turf
At stp (standard temperature and pressure), the temperature is T=0 C=273 K and the pressure is p=1.00 atm. So we can use the ideal gas law to find the number of moles of helium:

where p is the pressure (1.00 atm), V the volume (20.0 L), n the number of moles, T the temperature (273 K) and

the gas constant. Using the numbers and re-arranging the formula, we can calculate n:
Photons are particles of electromagnetic radiation.
The work done is by the centripetal force on mass m during an angular displacement of 2π revolutions mv²2π /r J
Centripetal force - a force acts on an moving object in circular path.
the centripetal force is given by
F= mv²/r (equation1)
Work done is given by
W = Fd (equation 2)
d = 2π
work is done by the centripetal force on mass m during an angular displacement of 2π revolutions is given by:
to calculate work done using equation 1 in 2 we get
W = mv² d/r
W = mv² × 2π /r J
The work done is by the centripetal force on mass m during an angular displacement of 2π revolutions mv²2π /r J
To know more about centripetal force :
brainly.com/question/13031430
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For a cylinder that has both ends open resonant frequency is given by the following formula:

Where n is the resonance node, v is the speed of sound in air and L is the length of a cylinder.
The fundamental frequency is simply the lowest resonant frequency.
We find it by plugging in n=1:

To find what harmonic has to be excited so that it resonates at f>20Hz we simply plug in f=20 Hz and find our n:

We can see that any resonant frequency is simply a multiple of a base frequency.
Let us find which harmonic resonates with the frequency 20 Hz:

Since n has to be an integer, final answer would be 323.