Gravity Pt1

Gravity

Part 1

By the end of this lesson you should ...

• ...know how gravity keeps each of the stars and galaxies together.

• ...understand the basics of how gravity works.

Standards

• 6.ESS.1 Describe the role of gravity and inertia in maintaining the regular and predictable motion of celestial bodies. 

Multiple Choice

What was Kepler's second law?

• Objects at rest tend to stay at rest

• Heliocentrism

• Planets orbit on an eliptical

• Planets move faster as they get closer to the sun.

Multiple Choice

Who came up with the ideas about inertia?

• Kepler

• Ptolemy

• Newton

• Copernicus

A Strong Pull

Why does Earth revolve around the sun? What keeps Earth and other objects in the solar system from spinning off into outer space? The same forces that keep your feet on the ground also keep the planets in orbit, but how?

Gravity

is a force of attraction that is universal because every mass exerts a pull on every other mass. That might sound confusing, but you already know a lot about gravity. Gravity pulls you (a mass) to the earth (another mass). It also pulls the earth toward you because gravity—or the gravitational force—is a mutual attraction between any two objects that have mass.

Mass

the amount of matter in an object.

So attractive!

So, is a gravitational force pulling you toward your computer? Are you being pulled toward your stapler, hole puncher, breakfast cereal, mailbox, and everything else in the universe? The answer is yes. But you don't feel the tug because the earth's mass is so much more than any of those objects. Its gravitational force pulling you and them to the ground is stronger.

Multiple Choice

True or False?

Gravity is a pull between all objects that have mass?

• True

• False

The Man Behind the Gravity

Sir Isaac Newton

Who was Newton?

Isaac Newton was a physicist and mathematician who studied motion of objects extensively. He developed the field of math called calculus. In his research, he developed the laws of motion and universal gravitation.

Discovering Gravity

Newton studied gravity over a period of two decades. Newton's focus on gravity was not whether or not it existed, but on how far the effects of gravity extended.

An Apple?

The common story about Newton and gravity involves an apple falling from a tree and hitting him on the head. This is most likely not true. However, acquaintances of Newton do recall him questioning why an apple falls the way it does.

Gravity and the Universe

Newton was able to apply his findings to the moon and other planets in the solar system. He was able to prove that it was gravity that caused elliptical orbits. He demonstrated that the effects of gravity are still very relevant at far distances.

Law of Universal Gravity

• 1. Every object in the universe exerts a gravitational force on every other object.

• 2. The size of the gravitational force depends on the mass of each object.

• 3. The size of the gravitational force depends on the distance between the objects.

Multiple Choice

Every object exerts a ______ on every other object.

• push

• pull

• electricity

• wave

Multiple Choice

The size of the gravitational force depends on the ____ of the object.

• weight

• size

• mass

• type

Multiple Choice

The size of the gravitational force depends on the ________ between the objects

• love

• electricity

• waves

• distance

Universal Force

• Newton's work proved Keplers theories.

• Newton's Laws apply to all objects in the universe with mass

• Planets orbiut stars because stars are more massive.

• Moons orbit planets because they are more massive.

Multiple Choice

True or False.

A planet is more likely to revolve around a star, than a star is to revolve around a planet.

• True

• False.

Mass and Weight

• Weight is the measure of the force of gravity on something

• Mass is how much matter is in something.

• Mass is the same no matter what

• Weight changes if you are on different planets

Multiple Choice

Planets that are closer togetther have a greater gravitational pull

• true

• false

Multiple Choice

Weight is the amount of force of gravity acting on an object.

• true

• false

Multiple Choice

Objects with larger masses will revolve around objects with smaller masses.

• true

• false

Multiple Choice

Mass and weight are the same.

• true

• false

Open Ended

How do you feel about gravity?