# Calculating the Net Force of Sun & Moon on Earth

• eclecticmanic
In summary, tides are created by the gravitational attraction of the sun and moon on Earth. The net force pulling on Earth during a New Moon is 5.29 x 10^33, during a Full Moon is 5.29 x 10^33, and during a First Quarter Moon is 2.645 x 10^33. This is due to the combined and opposite forces of the sun and moon at different positions relative to the Earth.
eclecticmanic
Tides are created by the gravitational attraction of the sun and moon on Earth. Calculate the net force pulling on Earth during a)New Moon b)Full Moon c)First Quarter Moon.
Mass of the Moon: 7.35 x 10^22 kg
Mass of the Earth: 5.98 x 10^24 kg
Mass of the Sun: 1.99 x 10^30 kg
Distance from the Earth to the Moon: 3.84 x 10^8 m
Distance from the Earth to the Sun: 1.50 x 10^11 m
Universal Gravitational Constant (G): 6.67 x 10^-11
F=Gmm/d²I solved for the force of Sun on Earth
F=(6.67 x 10^-11)(1.99 x 10^30)(5.98 x 10^24)/1.5 x 10^11 = 5.29 x 10^33

And Moon on the Earth
F=(6.67 x 10^-11)(7.35 x 10^22)(5.98 x 10^24)/3.84 x 10^8 = 7.63 x 10^28

I don't know where to go from there, I think finding the solution has to do with where the moon is facing and maybe it's the difference from the distance of the sun? help me please

Last edited:
Draw a digram with the relative positions of the earth, sun and moon.

There was a picture on my worksheet. I thought that during New Moon the Sun and moon act together on Earth so I added my answers 5.29 x 10^33 + 7.63 x 10^28=5.29 x 10^33.
For Full Moon I subtracted because I though the sun and moon were working in opposite forces
5.29 x 10^33 - 7.63 x 10^28=5.29 x 10^33...I get the same answer?? misinterpreting?

For Quarter since it looked half and half on the image, I divided the sum by 2.
5.29 x 10^33/2= 2.645 x 10^33. I'm still lost.

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A new moon (dark) is between the Earth and sun so their gravity combines
A full moon (bright) is opposite the Earth from the sun so it pulls in the opposite direction
A half moon is 90 deg ahead of the earth

I did not get that forces - did y square the distance or not?

## 1. How do you calculate the net force of the Sun and Moon on Earth?

To calculate the net force of the Sun and Moon on Earth, you need to use Newton's Law of Universal Gravitation. This formula takes into account the masses of the Sun, Moon, and Earth, as well as the distance between them. By plugging in these values, you can calculate the force of gravity exerted by each celestial body on Earth and then add them together to find the net force.

## 2. What is the significance of calculating the net force of the Sun and Moon on Earth?

Calculating the net force of the Sun and Moon on Earth is important because it helps us understand the forces at play that affect the Earth's orbit and rotation. This knowledge is crucial for predicting and understanding natural phenomena such as tides and eclipses.

## 3. How does the distance between the Sun and Moon affect the net force on Earth?

The distance between the Sun and Moon is a crucial factor in calculating the net force on Earth. As the distance between the two celestial bodies changes, so does the force of gravity exerted on Earth. When the Sun and Moon are aligned (during a new or full moon), their combined gravitational force is stronger, resulting in higher tides. When they are at a right angle (during a first or third quarter moon), their gravitational forces partially cancel each other out, resulting in lower tides.

## 4. Can the net force of the Sun and Moon on Earth change over time?

Yes, the net force of the Sun and Moon on Earth can change over time. This is due to the fact that the Earth, Sun, and Moon are all constantly moving and their positions relative to each other are not always the same. Additionally, the gravitational force between objects decreases as the distance between them increases, so as the Earth orbits the Sun, the distance between the Sun and Moon also changes, affecting the net force on Earth.

## 5. How does the net force of the Sun and Moon on Earth impact Earth's orbit and rotation?

The net force of the Sun and Moon on Earth plays a significant role in Earth's orbit and rotation. The gravitational pull of the Sun and Moon helps keep the Earth in its relatively stable orbit around the Sun, while the Moon's gravitational force also causes the Earth to experience tidal forces that affect its rotation. These forces can also cause slight changes in the Earth's axis, resulting in phenomena such as precession and nutation.

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