# HOMEWORK # 3

Flashcard maker : Gabriela Compton
Define: Falsifiable

Give an example

– A claim that CAN be tested

– Example: John F. Kennedy was the 35th president of the U.S.

Earth is located at one ____ of the Moon’s orbit

Define this term

– Focus

– One of two points within an ellipse that lie along the major axis

According to Kepler’s second law, Jupiter will be traveling most slowly around the sun when at _____

Define this term

– Aphelion

– The point at which an object orbiting the Sun is furthest from the Sun

The mathematical form of Kepler’s third law measures the period in years and the _____ in astronomical units (AU)

Define this term

– Semimajor axis

– The average distance of an orbiting object

According to Kepler’s second law, Pluto will be traveling fastest around the Sun when at ______

Define this term

– Perihelion

– The point where an object orbiting the Sun is closest to the Sun

The extent to which Mars’ orbit differs from a perfect circle is called its _______

Define this term

– Eccentricity

– A measure of how much an ellipse differs from a perfect circle

Tycho Brahe’s contribution to astronomy included:

A) Inventing the telescope

B) Proving that Earth orbits the Sun

C) Collecting data that enabled Kepler to discover the laws of planetary motion

C) Collecting data that enabled Kepler to discover the laws of planetary motion
Galileo’s contribution to astronomy included:

A) Discovering the laws of planetary motion

B) Discovering the law of gravity

C) Making observations and conducting experiments that dispelled scientific objections to the Sun-centered model

C) Making observations and conducting experiments that dispelled scientific objections to the Sun-centered model
Consider Earth and the Moon. As you should now realize, the gravitational force that Earth exerts on the Moon is equal and opposite to that which the Moon exerts on Earth. Therefore, according to Newton’s second law of motion __________

A) The Moon has a larger acceleration than Earth, because it has a smaller mass

B) Earth has a larger acceleration than the Moon, because it has a larger mass

C) The Moon and Earth both have equal accelerations, because the forces are equal

A) The Moon has a larger acceleration than Earth, because it has a smaller mass
Suppose you are in an elevator. As the elevator starts upward, its speed will increase. During this time when the elevator is moving upward with increasing speed, your weight will be __________

A) Greater than your normal weight at rest

B) Equal to your normal weight at rest

C) Less than your normal weight at rest

A) Greater than your normal weight at rest
Suppose you are in an elevator that is moving upward. As the elevator nears the floor at which you will get off, its speed slows down. During this time when the elevator is moving upward with decreasing speed, your weight will be __________

A) Greater than your normal weight at rest

B) Equal to your normal weight at rest

C) Less than your normal weight at rest

C) Less than your normal weight at rest
Your weight will be greater than normal when the elevator is moving upward with increasing speed. For what other motion would your weight also be greater than your normal weight?

A) The elevator moves upward with constant velocity

B) The elevator moves downward with constant velocity

C) The elevator moves upward while slowing in speed

D) The elevator moves downward while slowing in speed

E) The elevator moves downward while increasing in speed

D) The elevator moves downward while slowing in speed
If you are standing on a scale in an elevator, what exactly does the scale measure?

B) The force you exert on the scale

C) The gravitational force exerted on you by Earth

B) The force you exert on the scale
The light from Polaris travels through space in the form of ___ energy

Define this term

– Energy carried by light

Rapidly moving comets have more ____ energy than slowly moving ones

Define this term

– Kinetic energy

– Energy of motion

An apple contains _______ energy that your body can convert into other forms of energy

Define this term

– Chemical potential energy

– Potential energy that can be released through chemical reactions (food contains potential energy)

Nuclear fusion on starts converts some of the ___ energy of hydrogen nuclei into light and heat

Define this term

– Mass energy

– The potential energy of mass, which has an amount E=mc^2

Due to its much higher density, water heated to 80 degrees (Celsius) contains more ____ energy than air at the same temperature

Define this term

– Thermal energy

– The collective kinetic energy of the many particles in a substance

An astroid that is moving farther from the Sun is gaining _____ energy

Define this term

– Gravitational potential energy

– Energy that an object has because of its position in a gravitational field; the greater the distance an object can fall, the more a gravitational potential energy it has

True or False:
There is no gravity in space
False
As an interstellar gas cloud shrinks in size, its gravitational potential energy…

A) Stays the same at all times

B) Gradually transforms into other forms of energy

B) Gradually transforms into other forms of energy
According to the Law of Universal Gravitation, what would happen to Earth if the Sun were somehow replaced by a black hole of the same mass?

A) Earth would be quickly sucked into the black hole

B) Earth would slowly spiral in to the black hole

C) Earth’s orbit would not change

C) Earth’s orbit would not change
Compared to its angular momentum when it is farthest from the Sun, Earth’s angular momentum when it is nearest to the Sun is…

A) The same

B) Greater

C) Less

A) The same