Gravity and the Solar System

Notes

Engage your Brain T or F

• Draw into your notebook the picture of the effects of air resistance on a falling object. Label the picture. Use the picture of the apple on page 256.

1. Gravity keeps the planets in orbit around the sun. 2. The planets follow circular paths around the sun. 3. Sir Isaac Newton was the first scientist to describe how the force of gravity behaved.4. The sun formed in the center of the solar system.5. The terrestrial planets and the gas giants formed from the same material.

Facts about Gravity

Interesting:• When astronauts are in

orbit, Earth’s gravity still pulls them downward toward the planet. However, they experience weightlessness and appear to be floating. They “float” because everything around them is falling at the same speed.

1. Gravity is the weakest force in nature.

2. Gravity is the force that formed: planets, stars, and galaxies.

3. Gravity keeps smaller bodies in orbit around larger bodies.

Acceleration and Gravity

• What is acceleration?

• What is the rate at which objects accelerate toward Earth?

• Acceleration is the rate at which velocity changes over time.

• 9.8m/s2

Air Resistance and Gravity

• What force opposes the motion of objects through the air?

• What is terminal velocity?

• Air resistance

• As the speed of a falling object increases, air resistance increases.

• The point where the upward force of air resistance equals the downward force of gravity (net force = 0)

Centripetal Force and Gravity

• What is centripetal force?

• Gravity keeps the planets in orbits around the sun. If the gravitational pull disappeared, the planets would fly off.

• An inward force that causes an object to move in a circular path

LAW OF UNIVERSAL GRAVITATION

• Who was Sir Isaac Newton?

• What does the law of universal gravitation state?

• First scientist to mathematically describe how the force of gravity behaved.

• States that the force of gravity between two objects increases as the mass of the objects increases, and as the distances between them decreases

Ticket out

• The universe, the solar system and the planets and moons in the solar system all needed the force of gravity to form. Describe how gravity played a role in the formation of stars, planets, solar systems.

• Hint- think about the big bang theory- matter is flying out from a central spot . .. You may draw a picture and describe what is happening or you may write a short paragraph.