Orbital Motion and Gravity

What are the factors which combine to to keep celestial bodies in orbit? 

• Air Resistance and Gravity 
• Gravity and Inertia 
• Inertia and orbital speed
• Orbital speed and gravity 

The tendency of a moving object to continue moving in a straight line or a stationary object to remain in place is called:

• Orbital Speed 
• Gravity 
• Terminal Velocity 
• Inertia 

All objects are attracted to each other by the force of:

• Gravity 
• Inertia 
• Orbital Speed 
• Terminal Velocity 

The strength of the force of gravity depends on:

• the masses of the objects and their speeds.
• the masses of the objects and the distance between them.
• the weight of the objects and their speeds.
• the masses of the objects and their weights.

Which planet in our solar system will have the fastest orbital  speed?

• Venus 
• Earth 
• Saturn 
• Mercury 

What did Kepler discover about planets and their orbital speed?

• Planets closest to the Sun will orbit with the fastest orbital speed.
• Planets with the greatest mass will orbit the Sun with the fastest orbital speed.
• Planets furthest from the Sun will orbit with the fastest orbital speed.
• Planets with the least mass will orbit the Sun with the fastest orbital speed.

Which law states that every object in the universe attracts every  other object in the universe?

• Newton’s first law of motion
• Newton’s second law of motion
• The law of universal gravitation
• The law of inertia

According to Kepler’s discoveries, planets orbit around the Sun:

• in an oval shape.
• in perfect circles.
• in an ellipse.
• in a rectangular shape.

As mass increases, gravity ________________.

• Increases 
• Decreases 
• Stays the same 

As mass decreases, gravity ______________________.

• Increases 
• Decreases 
• Stays the same