Unit2 Lesson3 Flashcards
Law of Gravitation
What is scientific law?
In science, this means that the concept is well-proven and tested through exprical experiments and observations. The law will be in effect under certain conditions. The law describes a phenomenon or event and what will occur. Laws just describe what will happen; they don’t try to explain why.
Motion of the Planets?
We no know that our planet and all other objects in the solar system orbit our star due to gravity. This is probably the same thing that happens around most every star in the universe; other stars probably have planets, dwarf planets, and such that orbit them. This is all based on Kepler’s laws.
Who is Johannes Kepler?
Johannes Kepler, a German mathematician and astronomer, came up with three laws of planetary motion back in the early 1600s. He determined this even without understanding gravity. he plotted the paths of the planets as they moved across the sky and looked at years of data to develop his laws of planetary motion. His laws explain what will happen, not why? One of his three laws stats that planets orbit stars in elliptical paths.
Motion of the solar system
Objects in our solar system include our Sun, planets, dwarf planets, moons, comets, and asteroids. Kepler’s laws help describe the motion of planets around our star, the Sun, and the motion of moons as they orbit their planets. We now kow that our planet and all other objects in the solar system orbit our star due to gravity. This is probably the same thing that happens around most every star in the universe.; other stars probably have planets, dwarf planets, and such that orbit them. This is all based on Kepler’s laws.
Every object exerts a gravitational pull on every other object. Yes or No?
Yes, this is one of the fundamental forces in nature. Newton made many discoveries around the same time as Kepler. He was first able to identify gravity as a force and also to define gravity mathematically. He was the first to determine the laws of motion and then the law of universal gravitation that we will be learning about.
Newton’s Achievements.
- Came up with the term ‘gravity’
- 3 laws of motion
- 1st law: law of inertia: every object will stay at rest unless acted on by another force. It also means an object in motion will continue moving in the same direction and speed unless acted on by another object.
- 2nd law: a force is mass x acceleration
- 3rd law: there is an equal and opposite reaction to any motion event.
Where Newton’s laws can be applied?
Newton’s laws allow for just about every example of motion you can think of . If it hs to do with movement, Newton’s laws apply. What Newton wanted was to try to simplify his laws into one that could be used to tie together what happens on Earth and in space. He was able to bring these concepts together in the law of universal gravitation.
What is the Universal Law of Gravitation?
- Every particle of matter attracts every other particle of matter.
- Force of attraction is proportional to the product of masses of the particles. F = G M m /(r^2)
- G is universal gravitation constant
Universal Law of Gravitation: Mass of Objects
- According to Newton’s law of universal gravitation, every object with mass has a gravitational force.
- The more massive the object, the greater the force again, as long as the distance is kept the same.
- Objects with greater mass have a greater gravitational force.
First part of Gravitation Law
The first part of gravitation law is that the force due to gravity between two objects is dependent on the masses of the objects: the more massive the object, the more gravitational pull it could have as long as we keep the distance beteen the objects’centers the same for comparison.
Our Sun is massive; Earth orbits the Sun. Our Sun is so large there are at least eight planets, many asteroids, and comets that orbit it.
Second part of Gravitation Law
It means that the further the objects are from each other, the less their gravitational force on each other. The size of the distance is greater, and therefore the force due to gravity is lessened.
Why the Moon orbits Earth instead of just the Sun.
The Earth exerts a larger gravitational force on the Moon than the Sun does because we are so much closer to it.
Does the Moon exerts a gravitational force on the Earth?
Yes, the Moon has some pull. The Moon contributes to our ocean tides and even the tilt of our axis.
How the Earth’s gravitational force affect us?
Here on Earth we are so affected by Earth’s gravitational force that we can’t even leave without the assitance of a rocket. We are basically stuck to the surface! The gravitational force here is so large we can only jump a few feet off the surface. We are too close. The closer you are, the greater the force! We actually exert a gravitational force on the Earth, but is is so small compared to the Earth’s force we can’t really affect it that much.
