Quiz 1 Flashcards
Explain the difference between mass and weight.
Mass is the AMOUNT of MATTER in an object. Weight is a MEASUREMENT of the FORCE which acts upon an object. Think about the difference of the weight of a man on the Moon versus the Earth. The Earth has more gravity so the man weighs more on Earth, but the man’s mass stays the same on both because that does not change.
What is momentum? What quantities does it depend on?
Momemtum is the mass times velocity of an object.
What are three of Newton’s Laws of Motion?
- An object’s momentum does not change if left alone. (A ball sitting on a flat surface will not move so long as no external forces causes it to do so).
- A force can change the object’s momentum. (Push the ball and it will move)
- For any force, there is always an equal and opposite reaction force. (A spaceship will be lifted in the air just as the amount of smoke will be pushed out from the bottom)
What is the equation of gravity? Explain what each of the variables represents.
Fg = G (M1M2/d2)
The force of gravity is the gravitational constant of the universe times the mass of one object multiplied by the mass of another object and divided by the distance between the two objects squared.
What happens to the force of gravity if the distance between two objects is doubled?
The more distance increases, the more the force of gravity decreases. Therefore if the distance between two objects is doubled, the weaker the force of gravity.
Explain why an ice skater rotates faster when they bring their arms closer to their body?
Angular momentum = mass x velocity x radius. Extended arms mean larger radius and smaller velocity of rotation. Bringing in the arms decreases the radius and therefore increases rotational velocity.
Why are there two high tides per day on Earth?
Twice a say the Earth goes through two of the bulges, created by the Moon’s gravitational pull, experiencing two cycles of tides.
What is a lightyear?
A lightyear is the distance that light can travel in one year. One light year is equal to 5.88 trillion miles.
What is the difference between the “solar system” and “galaxy”?
Solar system has Sun and planets, and a galaxy is a collection of stars.
Name the two types of planets in our solar system and list the names of the planets that
belong to each of the two types.
Terrestrial (Mercury, Venus, Earth, and Mars) and Jovian (Jupiter, Saturn, Uranus, Neptune).
List at least three differences between the two types of planets.
Terrestrial planets are smaller in size and mass, made mostly of rock and metal and have a more solid surface, and closer to the Sun. Jovian planets are larger in size and mass, made mostly of gas (hydrogen, helium, and hydrogen compounds) and have no solid surface, and are farther from the Sun.
Why do all planets orbit the Sun in the same direction?
Because of the conservation of angular momentum (if there is no torque, the total angular momentum of a system remains constant). The rotating disk that the sun and planets are formed in thus rotate them all in one direction. The Sun is in the center and therefore the planets orbit the Sun in the same direction.
Why did the solar nebula form a disk as it collapsed?
Because the cloud collapses and as it collapses the cloud spins and collision between particles flattens the cloud into a disk.
How many people are there in all of history who have seen “the entire circle of the Earth”?
24
