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Topic Review:

Circular Motion

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3-1: The Gravitational Field

• ALL objects attract each other with a force of gravitational attraction. 

• The force depends on the mass of the objects and the distance between their centers.

Multiple Choice

Force of gravity is inversely proportional to

• Mass

• Weight

• Distance

• Time

Multiple Choice

If I double the distance between two objects, what happens to their gravitational Force?

• 4x bigger
• 4x smaller
• 2x bigger
• 2x smaller

Multiple Choice

If I double the mass of one object without changing anything else, What would happen to the gravitational force between that object and any other object?

• Doubles

• Quadruples

• Cut in Half

• $$\frac{1}{4}$$  as much

Multiple Choice

What happens to Gravitational force if I double both of the masses but don't change their distance?

• doubles

• half as big

• 4 times bigger

• $$\frac{1}{4}$$ as much or 4 times smaller

Multiple Choice

Find the distance between two objects whose masses are m₁ = 4,500 kg, and m₂ = 8,700 kg; if the gravitational force between them is F = 2.0 x 10^-8 N.

• 130565.25 m

• 361.34 m

• 0.19575 m

• 0.783 m

3-2: Angular Velocity & Centripetal Acceleration

• There are "circular" variables that correspond to linear variables.

• Change in Angle, Angular Velocity, and Centripetal Acceleration.

• There is also a Linear Velocity for objects in circular motion!

Multiple Choice

The rotational equivalent to x (displacement), v (velocity) and a (acceleration) are?

• m, m/s, m/s²

• θ, ω, α

• x, x/t, α

• μ, Σ, τ

Multiple Choice

Which of the following is NOT a unit of angular velocity?

• Meters per second

• Revolutions per minute

• Revolutions per second

• Rotations per second

Multiple Choice

A bug on a spinning record will make more turns per minute if it is located toward the center of the record.

• True

• False

Multiple Choice

Which represents the acceleration of the ball? The ball is moving counter-clockwise.

• A

• B

• C

• D

Multiple Choice

Where should you go on a merry go round to go fastest?

• Into the middle!

• Out to the edge!

• Doesn't matter- rotational speed and linear speed are the same everywhere!

• Jump up to go fastest!

3-3: Centripetal Force

• This is the name given to a force moving an object in uniform circular motion.

• ​If you lost the centripetal force the object would stop revolving and continue in a straight line tangent to the circumference of the circle.

• Time Period is the number of seconds it takes for one cycle, and the inverse is Frequency.

Multiple Choice

If mass increases force will....

• increase because they have a direct relationship

• increase because they have a inverse relationship

• decrease

• both

Multiple Choice

If radius increases force will....

• decrease because they have a direct relationship

• decrease because they have a inverse relationship

• increase

• both

Multiple Choice

If velocity increases force will....

• increase because they have a direct relationship

• increase because they have a inverse relationship

• decrease

• both

Multiple Choice

Decreasing the radius when making a turn allows you to____?

• Increase your friction
• Keep a high speed
• Change your inertia
• Decrease gravitational pull

Multiple Choice

The centripetal force of satellites is similar to gravitational force because they are both a net force towards the center of earth.

• True
• False

Multiple Choice

A dog sits 1.50 m from the center of a merry-go-round and revolves at a tangential speed of 1.80 m/s. If the dog’s mass is 18.5 kg, what is the magnitude of the centripetal force on the dog?

• 56 N

• 21 N

• 40 N

• 98 N

3.4 Applications of Circular Motion

• All planetary orbits are ellipses.

• Planets cover equal areas in equal time periods.

• Satellites move faster when closer to the sun, and slower when further away.

Multiple Choice

An ellipse is drawn around two points called

• aphelion
• perihelion
• foci
• axis

Multiple Choice

When a planet orbits the Sun, one of the foci of the elliptical orbit is 

• the axis
• the perihelion
• the center
• the Sun

Multiple Choice

The farther away a planet is from the sun, the _______ it takes it to orbit the sun once. 

• longer
• shorter

Multiple Choice

Earth will travel fastest in its orbit when

• the earth is closest to the sun (January 3rd)

• the earth is farthest from the sun (July 3rd)

Multiple Choice

The "Law of Harmonies" is which of Kepler's Laws?

• 1st
• 2nd
• 3rd
• 4th

Planetary Motion & Gravitation (Physics 7.1)

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Multiple Choice

Kepler's _____ Law states that the paths of the planets are ellipses, with the Sun at the center.

• 1st

• 2nd

• 3rd

• 4th

Multiple Choice

"An imaginary line from the Sun to a planet sweeps out equal areas in equal time intervals" is...

• Kepler's 1st Law

• Newton's 2nd Law

• Kepler's 2nd Law

• Newton's 3rd Law

Multiple Choice

"the square of the ratio of the periods of any two planets revolving about the Sun is equal to the cube of the ratio of their average distances from the Sun" is ________, also written as

$$\left(\frac{T_A}{T_B}\right)^2\ =\ \left(\frac{r_A}{r_B}\right)^3$$  

• Newton's 2nd Law

• Kepler's 2nd Law

• Kepler's 1st Law

• Kepler's 3rd Law