Answer:
Kepler's third law
Explanation:
As per Kepler's third law all planets revolve around the Sun in such a way that their square of time period of revolution around the Sun is proportional to the cube of the mean radius.
It is given as
here
c = proportionality constant
R = mean radius
T = time period around the sun
So here all celestial body and all planets revolve as per the Kepler's third law which is also known as law of harmonies
The wavelength is the so-called "fundamental" wavelength, or the "first mode." Thus, the wavelength of the string's vibration is defined by the supports, and has nothing whatsoever to do with mass or elasticity.
<span>Two characteristics of regular, periodic waveforms are :
</span><span>1) Amplitude - It is the </span><span>the length and width of waves, such as sound
waves, as they move or vibrate. An example would be how
much a radio wave moving back and forth.
</span><span>
2) Frequency - It is the number of waves cycles per unit of time, passing a
point per unit time. It is usually measured in Hertz.</span>
So you didn't provide any statements but I'll describe gravity for you and hopefully, it'll help.
Science: Gravity is the force that holds down objects and causes them to fall. It pulls down on an object, causing said object to fall or to remain in contact with the ground. Gravity is also what keeps the planets of our solar system in orbit of our sun and it keeps the planet's moon in orbit around the earth.
Gravity can also mean solemn importance, or seriousness of demeanor.
Hope this helps. :)
A is the answer to your question
20 minuets is 1/3 of an hour so you multiply 30 km by 3 and get 90 km/hr