How Does the Moon Influence Earth's Tides?

[Farcry25]

Homework Statement

Some people say that the tides on Earth are caused by the pull of the moon. Let us investigate whether this is true.

(a) Determine the forces that the moon and the sun exert on a mass, m, of water on Earth. Your answer will be in terms of m with units of N.


(c) Determine the difference in force exerted by the moon on the water at the near surface and the water at the far surface (on the opposite side of Earth), as illustrated in Figure 8-13.Again, your answer will be in terms of m with units of N.

(d) Determine the difference in force exerted by the sun on water at the near surface and water at the far surface (on the opposite side of Earth).


(f) Why is the statement that the tides are due to the pull of the moon misleading? Make a correct statement to explain how the moon causes tides on Earth.

figure 8-13 here
http://img361.imageshack.us/img361/2707/1111111111bs9.th.gif

Homework Equations

Idk where to start or how to do this can anyone just explain to me how to solve it please don't give me the answer bc i actually got to learn how to solve this types of problems

 

[mgb_phys]

The force of gravity is explained here http://en.wikipedia.org/wiki/Newton's_law_of_universal_gravitation

Tides are a little tricky - there are a couple of posts in this thread explaining tides.
wiki also has a good article.

 

[thomate1]

First, it is important to understand the concept of universal gravitation and how it applies to the forces exerted by the moon and the sun on Earth. Universal gravitation is a fundamental principle in physics that describes the attractive force between any two objects with mass. This force is directly proportional to the masses of the two objects and inversely proportional to the square of the distance between them.

Now, let's look at the forces exerted by the moon and the sun on a mass of water on Earth. The force exerted by the moon can be calculated using the equation F = GmM/r^2, where G is the gravitational constant, m is the mass of the water, M is the mass of the moon, and r is the distance between the two objects. Similarly, the force exerted by the sun can be calculated using the same equation, but with the mass of the sun (S) and the distance between the sun and the water (d).

(a) The forces exerted by the moon and the sun on the water can be calculated as follows:

Fmoon = GmMmoon/rmoon^2
Fsun = GmMsun/rsun^2

(c) The difference in force between the moon's pull on the near surface and the far surface of the water can be calculated by subtracting the force at the far surface from the force at the near surface:

Fmoon,near - Fmoon,far = GmMmoon/(d-R)^2 - GmMmoon/(d+R)^2

(d) Similarly, the difference in force between the sun's pull on the near surface and the far surface of the water can be calculated as:

Fsun,near - Fsun,far = GmMsun/(d-R)^2 - GmMsun/(d+R)^2

(f) The statement that the tides are due to the pull of the moon is misleading because it implies that the moon's pull is the only factor causing tides on Earth. In reality, the sun also plays a significant role in causing tides due to its larger mass. A more accurate statement would be that the tides on Earth are caused by the combined gravitational forces of the moon and the sun. As the Earth rotates, the water on its surface experiences a changing gravitational force from these celestial bodies, resulting in the rise and fall of tides.