Planetary Motion

Planetary Motion

The Moon, the planets, the Sun, and the stars all rotate around the Earth (which stays still), with uniform circular motion.

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​Geocentric Model

The Moon, the planets, the Earth, and the stars all rotate around the Sun (which stays still), with uniform circular motion.

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​Heliocentric Model

Multiple Choice

Heliocentric model is Earth-centered.

• True

• False

Multiple Choice

Geocentric model Earth-centered.

• True

• False

Fill in the Blank

The earth is at the center according to _______ model.

Fill in the Blank

The Sun is at the center according to _______ model.

Kepler's Laws of Planetary Motion

The planets move around the Sun in elliptical orbits.

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​Kepler's First Law

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A line running from the sun to the planet sweeps out equal areas of the ellipse in equal times.​

​Kepler's Second Law

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The squares of the orbital periods of the planets are directly proportional to the cubes of the semi-major axes of their orbits.

​Kepler's Third Law

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Multiple Choice

According to Kepler's Model planets travel in ____ orbits.

• elliptical

• circular

Multiple Choice

The closer a planet is to the sun the ____ distance is covered in the same time.

• more

• less

• same

Multiple Choice

The closer an orbiting object is to the sun, the _____ it travels.

• faster

• slower

Multiple Choice

Which force is required to maintain a body in uniform circular motion?

• Muscular force

• Gravity force

• Centripetal force

• Friction force

Multiple Choice

Which of the following is the correct definition of centripetal force?

• The force that acts away from the centre of the circle when an object is moving on a circular path, is known as centripetal force.

• The force that acts between two masses separated from each other by a certain distance, is termed as the centripetal force.

• The force that acts between two static charges separated from each other by a distance is termed as the centripetal force.

• The force that acts towards the center of the circle when an object is moving on a circular path, is known as centripetal force.

Multiple Choice

Which of the following changes when a body performs uniform circular motion?

• Mass

• Speed

• Kinetic energy

• Direction

Multiple Choice

When a girl rotates a stone tied to a string by swirling the string what force does her hand exert on the string?

• Centrifugal

• Centripetal

Multiple Select

What are the changes in a uniform circular motion?

• velocity changes

• direction changes

• speed changes

• mass changes

• acceleration changes

Multiple Choice

What is centrifugal force?

• The force that acts away from the centre of the circle when an object is moving on a circular path, is known as centrifugal force.

• The force that acts between two masses separated from each other by a certain distance, is termed as the centrifugal force.

• The force that acts between two static charges separated from each other by a distance is termed as the centrifugal force.

• The force that acts towards the center of the circle when an object is moving on a circular path, is known as centrifugal force.

Multiple Choice

What is the difference between centripetal and centrifugal forces?

• Centripetal is towards center while centrifugal is away from the center.

• Centrifugal is towards center while centripetal is away from the center.

Multiple Choice

Which of the following terms means "center fleeing"?

• centrifugal

• centripetal

Multiple Choice

Which of the following is the unit for centripetal force?

• J
• m/s²
• kg⋅m/s
• N

Multiple Choice

What is the relationship between centripetal force and the mass of an object?

• direct

• inverse

Multiple Choice

If centripetal force stopped acting on all satellites they would continue traveling in space in a constant direction and constant speed.

• True
• False

Multiple Choice

A car is rounding a bend as shown in the diagram. Which arrow correctly shows the direction of the cars velocity?

• A

• B

• C

• D

Multiple Choice

If car A and car B are both traveling at the same speed, which will require a higher centripetal force?

• Car A

• Car B

• They have the same centripetal force

Thank You