Unit2 Lesson1

Question 1

What is the force of Gravity?

Answer 1

• Gravity is a natural force by which all things with mass are brought toward each other: like planets, stars, or galaxies.
• It’s the reason your weight on the moon would 16.5% of your weight on earth.
• Gravity is dependent on the mass of the objects. The more mass an object has the more gravity it has.
• Gravity is a non-contact force. It is the force that keeps you stuck on earth and that keeps the earth revolving around the sun.
• Some interactions happen even when objects are not touching, and the most familiar of these involves gravity.
• Gravity is one of only four fundamental forces in the universe, and it causes literrally all objects with mass in the unverse to be mutually attracted.

Question 2

Since all mass is attracted to all other mass in the universe, it is also true that the Sun itself pulls on every student in a class. The star Alpha Centauri is many times more massive than the Earth, so why don’t students fly up in the sky towards that star or any of the others?

Answer 2

The strength of the gravitional force also depends the distance between the two objects.

Question 3

The Golden Gate Bridge pulls on the Hollywood sign (and every student in the state) just like the Moon pulls on the Earth. Why don’t we notice this pull?

Answer 3

This pull is so weak compared to the attraction toward Earth itself that is beacuse the planet has so much more mass than the Hollywood sign or even the Golden Gate Bridge.

Question 4

Gravity on Earth is usually thought of as pulling objects towards the center of the planet, but there is nothing particularly special about:

Answer 4

• The mass at the center of the planet
• The downward direction

Question 5

How does a person get pulled by the Earth?

Answer 5

A person gets pulled by every piece of the entire planet, with the rock directly beneath his or her feet exerting the strongest pull and the rock on the opposite side of the planet having the weakest because of its distance away.

Question 6

Have you ever wondered why things seem to float around in space, but on Earth they don’t?

Answer 6

• It’s all about gravity. Gravity is a force of attraction between any two obects that have mass.
• This attraction is when two objects with mass are drawn to each other due to the force between them. Any two objects that have mass have a gravitational force.

Question 7

Gravitational Force

Answer 7

• Everything exerts a gravitational force, even you!
• The force of gravity depends on the mass of the objects and how far apart they are.
• Since our mass is so small compared to that of the earth we cannot feel the effects of our own gravity.
• The force of gravity acts between all objects.
• If mass increases, the force of gravity increases.
• If distance increases, the force of gravity decreases.

Question 8

Why gravity is difficult to model?

Answer 8

Because it is an invisible force. We cannot see it doing the work. On Earth we are also experiencing gravity and we cannot turn it off.