Astro 115 Midterm
Newton's First Law
A body will remain at rest or continue to move with constant velocity unless acted upon by a net outside force. ex. When someone falls off of a skateboard, the board often keeps going until it hits something, since it feels very little frictional force to slow it down
What does 3.67 x 103 mean? A. 3670 B. 3673 C. 11.01 (or 3.67 x 3) D. 3.673 E. 1101 (or 367 x 3)
A. 3670
Total orbit energy (TOE) is the sum of the kinetic (KE) and gravitational potential energy (GPE) of an orbit. Which describes what happens to kinetic, gravitational, and total orbit energy of a planet during an orbit? A. KE is maximum when closest to the Sun, GPE is maximum when farthest away, and TOE never changes B. KE is maximum when farthest from the Sun, GPE is maximum when closest, and TOE never changes. C. KE, GPE, and TOE are all maximum when closest to the Sun. D. KE, GPE, and TOE are all maximum when farthest from the Sun.
A. KE is maximum when closest to the Sun, GPE is maximum when farthest away, and TOE never changes
The key property of a hypothesis that makes it scientific is that it should be A. Testable B. Correct C. Old D. Complex
A. Testable
Two identical spacecraft are accelerated by rocket engines. The second spacecraft has twice as much mass as the first. Which has a higher acceleration? A. The first spacecraft: it has less mass. B. The second spacecraft: it has a greater mass. C. They have the same acceleration because they experience the same force.
A. The first spacecraft: it has less mass.
Why do we experience spring tides? A. The high tides from the Sun and Moon occur in the same places at a given time. B. The Moon pulls on one side of the Earth and the Sun pulls on the other side. C. The Sun's tide becomes stronger than the Moon's tide. D. The high tides from the Sun and Moon occur in different places at a given time.
A. The high tides from the Sun and Moon occur in the same places at a given time.
Once a scientist (or group of scientists) finds an interesting result, what process must they go through to have their results published in a scientific journal? A. The result must be sent to another scientist who will look for errors. B. The result must be published on a web site. C. The calculations must be redone on a computer.
A. The result must be sent to another scientist who will look for errors.
Over the course of one night, an observer at any given location on the Earth sees the constellations gradually shift across the sky from east to west. This is caused primarily by A. The spin of the Earth on its own axis B. The wind C. The orbit of the stars around the Earth D. The orbit of the Earth around the Sun
A. The spin of the Earth on its own axis
Are there stars that never appear to set as seen from Southern California? A. Yes, stars near the celestial equator appear to stay up all of the time. B. No, all stars appear to rise and set. C. Yes, all stars appear stationary in the sky. D. Yes, stars near the North Star appear to circle around this point without setting.
A. Yes, stars near the celestial equator appear to stay up all of the time.
An object orbiting the Sun in a circle can be said to be A. always accelerating. B. moving at a constant velocity. C. moving under the action of equal and opposite forces. D. free of the Sun's gravity.
A. always accelerating.
When we dropped a ball and a truck, which felt a larger force from gravity? A.The truck, since it is more massive. B. The ball, since it is lighter. C. Neither, since they accelerate by the same amount.
A.The truck, since it is more massive.
Which constellation will the Sun be blocking in 6 hours? Where will Aries be in your sky 6 months later at midnight?
After six hours the sun will still be blocking Aries but since the earth has moved the sun appears to be setting on the horizon. Six months later the Aries constellation will be seen overhead because the earth will have gone half way around its orbit and be right in front of Aries, considering it is midnight you are therefore facing away from the sun.
Your employer gives you a chance to decide how long your break should be. Which one should you select? A. 1 centisecond. B. 1 kilosecond. C. 1 nanosecond. D. 1 second.
B. 1 kilosecond
Which of the following is an example in which you are traveling at constant speed but not at constant velocity? Rolling freely down a hill in a cart, traveling in a straight line A. Driving backward at exactly 50 km/hr B. Driving around in a circle at exactly 100 km/hr C. Jumping up and down, with a period of exactly 60 hops per minute D. None of the above
B. Driving around in a circle at exactly 100 km/hr
In the northern hemisphere, the stars rise in the East, set in the West and spin counter-clockwise around the North celestial pole. In the southern hemisphere the stars rise in the A. East, set in the West and spin counter-clockwise around the South celestial pole. B. East, set in the West and spin clockwise around the South celestial pole. C. West, set in the East and spin clockwise around the South celestial pole. D. West, set in the East and spin counter-clockwise around the South celestial pole.
B. East, set in the West and spin clockwise around the South celestial pole.
Consider swinging on a swing. How do kinetic energy (KE) and gravitational potential energy (GPE) change as you swing? A. GPE and KE are both maximum at the top of the arc. B. GPE is maximum at the top of the arc, while KE is maximum at the bottom of the arc. C. KE is maximum at the top of the arc, while GPE is maximum at the bottom of the arc. D. GPE is maximum before you start to swing, while KE is maximum when you stop swinging.
B. GPE is maximum at the top of the arc, while KE is maximum at the bottom of the arc.
Our solar system consists of A. the Sun and several nearby stars, as well as the planets and other objects that orbit these stars. B. the Sun and all the objects that orbit it. C. a few hundred billion stars, bound together by gravity. D.the Sun and the eight planets, and nothing else.
B. The sun and all the objects that orbit it
Suppose you lived on the Moon. Which of the following would be true? A. Both your weight and your mass would be less than they are on Earth. B. Your weight would be less than your weight on Earth, but your mass would be the same as it is on Earth. C. Your mass would be less than your mass on Earth, but your weight would be the same as it is on Earth. D. Both your weight and your mass would be the same as they are on Earth.
B. Your weight would be less than your weight on Earth, but your mass would be the same as it is on Earth.
The Earth experiences seasons because A) The Earth's spin slows down and speeds up, changing the length of the day. B) The distance to the Sun changes as we orbit it. C) The tilt of the Earth's spin axis causes different hemispheres to get more or less sunlight. D) The Moon reflects more or less light towards the Earth.
C) The tilt of the Earth's spin axis causes different hemispheres to get more or less sunlight.
A car moving at 30 miles/hour has roughly 100,000 J of kinetic energy. You need to keep your foot on the gas to maintain your speed (assume a flat road). The gas you burn represents 500 J of chemical energy every second. After 5 minutes, how much kinetic energy does your car have? A. More than 100,000 J B. Less than 100,000 J C. 100,000 J D. You need more information to tell
C. 100,000 J
The water on the side of the Earth that faces away from the Moon experiences: A. No tidal force B. Either a high tide or a low tide, depending on the angle to the Sun C. A high tide because the Moon in effect pulls the solid Earth out from under the water on the far side D. A low tide because all Earth's water is pulled toward the side of Earth that faces the Moon
C. A high tide because the Moon in effect pulls the solid Earth out from under the water on the far side
The formation of our solar system occurred A. Shortly before the age of the dinosaurs, around 250 million years ago. B. When the first hominids appeared around 5 million years ago. C. Around 4.6 billion years ago, billions of years after the universe formed. D. When the universe formed (around 14 billion years ago).
C. Around 4.6 billion years ago, billions of years after the universe formed.
Io orbits Jupiter at the same distance that Titania orbits Uranus. However, Io takes 1.7 day to orbit while Titania takes 8.7 days. What does this tell us? A. Io has more mass than Titania B. Titania has more mass than Io C. Jupiter has more mass than Uranus D.Uranus is farther from the Sun than Jupiter
C. Jupiter has more mass than Uranus
When 2 bodies fall, which hits the ground first? A. The heavy one B. The light one C. Neither - They hit at the same time
C. Neither - They hit at the same time
A friend exclaims that a few months ago she saw the full moon overhead at noon. Is this possible? A. Yes, because a full Moon is caused when the Moon is fully lit by the Sun, which can only happen at noon. B. Yes, but only if she was approximately 45 degrees from zero latitude. C. No, the full Moon is never overhead at noon.
C. No, the full Moon is never overhead at noon.
Sound travels at a speed of 300 meters per second. In analogy to the light-year, what does 1 sound-minute equal? A. The time sound takes to travel 300 meters. B. The time delay of a sound heard 300 meters away. C. The distance traveled by sound in 1 minute. D. The speed of sound 1 minute later.
C. The distances traveled by sound in 1 minute
Consider lifting a ball straight up into the air at a constant speed. There are two forces acting on the ball: gravity and the push from your hand. Which force is larger? A. The upward force from your hand. B. The downward force from gravity. C. The two forces are the same.
C. The two forces are the same.
Which of the following best describes the origin of ocean tides on Earth? A. Tides are caused on the side of the earth nearest the Moon because the Moon's gravity attracts the water. Tides are caused primarily by the gravitational force of the Sun. B. The Moon's gravity pulls harder on water than on land, because water is less dense than rock. C. Tides are caused by the difference in the force of gravity exerted by the Moon across the sphere of the earth. D. Tides are caused by the 23 1/2o tilt of the earth's rotational axis to the ecliptic plane.
C. Tides are caused by the difference in the force of gravity exerted by the Moon across the sphere of the earth.
Imagine a planet whose spin axis is perpendicular to its orbital plane. How would you describe its seasons? A. more extreme than those on Earth. B. longer than those on Earth. C. constant through the year. D. the same as those on Earth.
C. constant through the year.
The Earth's shadow falling on the Moon is the reason we see A) solar eclipses B) The Earth's shadow can never fall on the Moon because the orbit of the Moon around the Earth is inclined by 5 degrees to the orbit of the Earth around the Sun. C) the phases of the Moon D) lunar eclipses
D) lunar eclipses
The formula E = mc2 tells us that A. A large amount of mass can be converted into a small amount of energy. B. A small amount of energy can be converted into a large amount of mass. C. A small amount of mass can be converted into a small amount of energy. D. A small amount of mass can be converted into a large amount of energy.
D. A small amount of mass can be converted into a large amount of energy.
The Sun is A. Similar to other stars but much bigger and brighter. B. Very different from other stars (since it is made mostly of gases). C. Very different from other stars (since it generates its own light). D. An ordinary star.
D. An ordinary star
Why do we see different phases of the Moon? A. Because more (or less) of the Earth's shadow falls on the Moon's surface as the Moon orbits the Earth B. Because the Moon changes its distance from the Earth as it moves in its elliptical orbit, appearing to vary in brightness C. Because the illuminated hemisphere becomes more (or less) visible from Earth as the Moon spins on its axis D. Because more (or less) of the half of the Moon that is lit up by the Sun becomes visible as the Moon orbits the Earth
D. Because more (or less) of the half of the Moon that is lit up by the Sun becomes visible as the Moon orbits the Earth
Arrange the following items according to size, from the smallest to the largest. A. Earth, Sun, galaxy, solar system, giant star. B. Earth, Sun, giant star, galaxy, solar system. C. Earth, giant star, Sun, galaxy, solar system. D. Earth, Sun, giant star, solar system, galaxy.
D. Earth, Sun, Giant Star, Solar system, galaxy
Why doesn't the Moon crash into the Earth? A. The Moon's gravity pulls it away from the Earth. B. The Sun's gravity pulls it away from the Earth. C. The reaction force from the Earth's gravity pulls the Moon away from the Earth. D. The Moon is moving fast enough to avoid hitting the Earth.
D. The Moon is moving fast enough to avoid hitting the Earth.
Why is it more dangerous to put your hand in boiling water (212 F) than in a hot oven (350 F)? A. The water is hotter than the air in the oven. B. The water is cooler than the air in the oven. C. The water has less thermal energy than the air in the oven. D. The water has more thermal energy than the air in the oven.
D. The water has more thermal energy than the air in the oven.
In what sense are we "star stuff"? A. We could not survive without light from our star, the Sun. B. Our overall chemical composition is about the same as that of stars. C. Movie stars and other people are all made of the same stuff, so we all have the potential to be famous. D. We are made from the debris of previous generations of stars.
D. We are made from the debris of previous generations of stars.
Why are astronauts weightless in the Space Station? A. because the Space Station is so big B. because the Space Station is moving at constant velocity C. because there is no gravity in space D. because the Space Station is constantly in free-fall around the earth
D. because the Space Station is constantly in free-fall around the earth
A person on Earth sees a total solar eclipse. What would someone else standing on the side of the Moon facing the Earth see at this time? The Earth's A. night side. B. day side, which doesn't change in brightness. C. day side, which becomes completely dark. D. day side, with a dark spot that moves across it.
D. day side, with a dark spot that moves across it.
Orion is visible on winter evenings but not summer evenings because of A. baseball on television. B. the precession of the earth's axis. C. the tilt of the earth's axis. D. the location of the earth in its orbit. E. interference from the full moon.
D. the location of the earth in its orbit.
When we convert from kilometers to meters, we multiply by 1000 m/ 1 km. We can do this because A. there are 1000 km in one meter. B. all conversion require that we multiply by 1000, regardless of the units. C. meters and kilometers are the same thing. D. this fraction is equal to one.
D. this fraction is equal to one.
Light from the nearest stars to the Sun takes A. Over 2 million years to reach the Earth. B. About 6 hours to reach the Earth. C. Around 8 minutes to reach the Earth. D. About 100,000 years to reach the Earth. E. Around 4 years to reach the Earth.
E. Around 4 years to reach the earth
You are standing on the Earth. It is noon and the Sun is between you and the constellation Aries. Which direction in your sky is Aries?
If you are standing on the earth, its noon and the sun is between you and the constellation, then the would be overhead because at noon the sun is overhead and since it's blocking Aries it is also overhead.
How does changing your location on Earth affect the motion you see in the sky?
Moving east or west doesn't change your view of the sky, but it does change what time it is. Near the equator most or all stars rise in the east and set in the west. This is because the celestial poles (the stationary points on the celestial sphere) are on the northern and southern horizons. Near the north pole the stars remain up all of the time, circling around the celestial pole in a counterclockwise direction as the Earth spins because the north celestial pole is right over your head. If you are between the two, you get a mixture of these two kinds of motion: stars near the north celestial pole remain up all of the time while stars further south rise in the east and set in the west. This is because the north celestial pole is part way up from the northern horizon. In the southern hemisphere, the motion is similar to the northern hemisphere - objects move east to west, but it's the south celestial pole that is in your sky rather than the north so stars appear to circle this in a clockwise direction.
How does the Earth's motion affect our view of the sky?
On a daily basis the Earth spins eastward on its axis. This causes the Sun and the stars to rise in the east and set in the west. On a yearly basis, the Earth orbits around the Sun. At any one moment we can see half of the sky. As the Earth spins through the night we can see almost all of the sky (except the part blocked by the Sun and the portion too far south for us to see). The Earth's spin also causes time zones. The location of the Sun in your sky (or below your feet) determines what time it is locally, and since the Earth is a round spinning ball this is different in different locations on Earth.As the Earth orbits around the Sun we see different constellations up at a particular time of night. This also changes what part of the sky the Sun is blocking - the path the Sun makes through the year is called the ecliptic and the constellations along the ecliptic are called the zodiac.
You are standing on the Earth. It is noon and the Sun is between you and the constellation Aries Which direction will it be in 6 hours
Six hours later it will have appeared to shift and you will be able to see it off to the West horizon. This is due to earths spin.
What causes seasons to happen? (Diagram)
The earth equator is tilted based on its path around the sun. When it is summer the part of the earth that is facing the sun is receiving direct sunlight. Whereas when it is winter the sun does not hit the ground directly and this part of earth is facing away from the sun.
Imagine you are standing on the surface of the Moon, on the side facing the Earth. Would you see the Sun rise and set? Would you see the Earth rise and set?
The earth would not appear to rise or set because the same side of the moon is always facing the earth, therefore, it will always be in view. The sun, however, would appear to rise and set because as the moon revolves around the earth it keeps one side to the earth meaning that both sides get exposed to the sun making it appear as if the sun is rising and setting. When the moon is in front of the earth and sun the sun will appear high in the sky but when the moon is between the sun and earth the sun won't be visible making it appear that the sun is rising and setting.
How does the Moon's motion cause phases? (Diagram)
The reason for this is connected to the fact that we see the Moon by reflected sunlight. ½ of the Moon's surface is lit up by the Sun. In parts of its orbit around the Earth, that side is mostly facing towards the Earth, and we see full and gibbous phases. In other parts of the orbit, the lit up side of the Moon is mostly facing away from us and we see crescent and new phases.
Newton's Second Law
The size of the net force acting on a body equals the mass of the body times the acceleration (change in velocity) it feels, or F = ma. ex. whenever you catch a ball, you have to exert a force on it to stop its motion (otherwise it hits your face).The more massive the ball is, the more force you have to exert to stop it. The faster the ball is moving, the more force you have to use as well.
Describe the major components of the solar system
We live in a Solar system consist of 8 planets (which includes earth) that orbit the sun, along with those planets moons. Planets are objects that orbit the sun and are large enough to be spherical in shape, and gravity is strong enough scatter most other objects near them. Some are smaller terrestrial planets that consist mostly of hydrogen, helium, hydrogen compounds like water and methane. There are comets and asteroids that are orbiting the sun. Asteroids are rocky bodies that are orbiting around jupiter and mars. Then the sun itself, which makes up 99.8 % of the mass of the solar system.
An asteroid hits Mars. It exerts a force of 2 x 1013 Newtons. The impact lasts for 1.2 seconds. The Mars has a mass of 0.1 Earth masses. (a) Calculate the acceleration Mars will have during this period?
a. F=ma , a=F/m .1 earth masses (6 x 1024 kg/ 1 earth mass) = 6 x 1023 kg a= (2 x 1013 kg m/s2)/ (6 x 1023kg) = 3.3 x 10−11 m/ s2
How are stars and galaxies related?
stars are hot balls of mostly hydrogen and helium. The distances to stars are generally measured in light years. A light year is the distance a beam of light travels in 1 year. The nearest stars are 4 light years away. Stars come in a wide range of sizes from tiny red dwarfs to giant and supergiant stars that could fill up most of our solar system. A galaxy is a large collection of stars and (often) gas held together by gravity. Our Sun is one of the 200 billion stars that make up our Milky Way galaxy. The galaxy has a roughly disk shape around 100,000 light years across. The Sun is roughly 28,000 light years from the center of the galaxy. In addition to stars there are clouds of gas. Some of these clouds are the remnants of stars that have died while others are in the process of collapsing to form new stars.
Newton's Third Law
whenever a body exerts one force on another, the second body exerts an equal and opposite force on the first body. ex. When you fall down, it hurts because the ground hits you just as hard as you hit the ground
An asteroid hits Mars. It exerts a force of 2 x 1013 Newtons. The impact lasts for 1.2 seconds. The Mars has a mass of 0.1 Earth masses. (b) How much will Mars' velocity change?
Δv=at Δv = (3.3 x 10−11 m/s2) x 1.2 sec = 3.96 x 10−11 m/s
