Answer:
The direction of the net force is in the same direction as the acceleration. So for an object moving in a circle, there must be an inward force acting upon it in order to cause its inward acceleration. This is sometimes referred to as the centripetal force requirement.
Explanation:
How much of the earth's animal life exists in the oceans?
80% is the answer.
Answer:
Speed of an EM wave is different in air and in water.
Explanation:
The speed of an EM wave is different in air and water .
Since the frequency of any EM wave is its characteristic property, therefore wavelength and speed of EM wave Change on changing the medium of propogation.
Also the refractive index of any medium is defined as the ratio between light's speed in vacuum to the light's speed in any medium.
Also ,it can be define as speed of any EM wave in any medium = c/refractive index of medium.
Here, c is the speed of light, .
This sounds pretty easy, in fact. The orbital motion can be assumed to be circular and with constant speed. Then, the period is the time to do one revolution. The distance is the length of a revolution. That is 2*pi*R, where R is the distance between the Moon and the Earth (the respective centers to be precise). In summary, it's like a simple motion with constant speed:
v = 2*pi*R/T,
you have R in m and T is days, which multiplied by 86,400 s/day gives T in seconds.
Then v = 2*pi*3.84*10^8/(27.3*86,400) = 1,022.9 m/s ~ 1 km/s (about 3 times the speed of sound :)
For the Earth around the Sun, it would be v = 2*pi*149.5*10^9/(365*86,400)~ 29.8 km/s!
I know it's not in the problem, but it's interesting to know how fast the Earth moves around the Sun! And yet we do not feel it (that's one of the reasons some ancient people thought crazy the Earth not being at the center, there would be such strong winds!)