Unit 2 - Kepler's Laws

On the diagram, label where the planet is moving the fastest, second fastest, and slowest.

a

b

c

slowest

second fastest

fastest

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NGSS.MS-ESS1-2

NGSS.MS-PS3-1

Suppose you could change the properties of the Earth and the Moon. Arrange the changes you could make based on how they would affect the force of gravity between the two.

Groups:

(a) Increase gravity

,

(b) Decrease gravity

,

(c) Will not affect gravity

• Increase the distance between the two

• Move the Moon closer to the Earth

• Decrease the Earth's mass

• Increase the volume of the Earth

• Increase the Moon's speed around the Earth

• Increase the Moon's mass

Tags

NGSS.MS-ESS1-2

NGSS.MS-PS2-4

NGSS.MS-PS2-5

Planets orbit their stars in an ellipse with the ​ (a)   at one of the foci (centers) of the ellipse. A ​ (b)   is a special type of ​ (c)   where the distance between the foci is ​ (d)   .

​

• circle
• ellipse
• star
• zero
• planet
• greater than one
• less than one

Tags

NGSS.MS-ESS1-1

NGSS.MS-ESS1-2

The gravitational force between two objects can be increased by ​ (a)   the mass of the objects, and by ​ (b)   the distance between the objects.

• increasing
• decreasing

Tags

NGSS.MS-PS2-2

NGSS.MS-PS2-4

A physics teacher steps on a scale at the doctor's, and the scale reads about 1000 N. This is the force of gravity the Earth is pulling down on her with.

How strong is the force of gravity she is pulling up on the Earth with?

• 1000 N

• 10 m/s^2

• 10000 N

• Basically 0 N (because the Earth is so much larger).

Tags

NGSS.MS-PS2-1

The force of gravity between the Earth and the Moon is about 2 * 10^20 N (only 100 times less than the gravity between the Earth and the Sun!).

Why doesn't the Moon fall into the Earth?

• The Moon is falling towards the Earth, but it is too slow to measure.

• The Moon is falling towards the Earth, but it keeps missing.

• The gravity of the Sun pulls the Moon away from the Earth with a much stronger force.

• The Moon is too large for the 2 * 10^20 N to actually move it.

Tags

NGSS.MS-ESS1-2

NGSS.MS-PS2-4

NGSS.MS-PS2-5

Is there a gravitational force between two people standing 10 m apart?

• Yes, but it is too small to easily notice.

• No, only planets and stars generate gravitational forces.

• No, they are not big enough to have a gravitational force.

• Yes, but electrostatic repulsion is a much stronger force.

Tags

NGSS.MS-PS2-4

NGSS.MS-PS2-5

Imagine you're in an elevator that suddenly begins to descend. You know that the feeling of suddenly becoming lighter is because the elevator is accelerating downward (and not because gravity got weaker).

What other change would NOT produce the same feeling?

• You were on a much smaller planet.

• You were on a much larger planet.

• You were in an airplane moving downwards.

• You were suddenly farther away from the center of the planet.

Tags

NGSS.MS-PS2-2

NGSS.MS-PS2-4

Comets have very, very large elliptical orbits around their stars. Which demonstrates how a comet travels much faster near the sun compared to when it is farthest away?

• Kepler's 1st Law: orbits have their star at one focus of an ellipse.

• Kepler's 2nd Law: sattelites sweep equal areas in equal times.

• Kepler's 3rd Law: a sattelite's orbital period is proportional to its orbital radius.

• Kepler's 4th Law: F(net) = ma

Tags

NGSS.HS-ESS1-4

What is the definition of an ellipse?

• All points equidistant from a single point.

• All points that are equidistant to the sum of the distance between two points.

• All points equidistant to the difference of the distance between two points.

• All points equidistant to the sum of the distance between a fixed point and a line.