Astronomy chapter 5 and chapter 6 homework
The distance from the Earth to the Sun is
1 AU
Comets are usually made of
ice and possibly frozen gas
The gravitational attraction of the Earth for other objects,
is smaller for objects farther from the Earth but never vanishes entirely
What total force will cause an object with a mass of 5kg to gain 10 meters per second every second?
50 newtons
Which of these sequences places the outer planets in the correct order from the Sun, from the closest to the farthest.
Jupiter, Saturn, Uranus, Neptune (farthest)
A rocket is in a roughly circular orbit near the surface of the Earth, moving at around 5 miles per second. Suppose that it is desired to lower it to a new circular orbit, slightly closer to the surface. The rocket flips over and fires its main rocket engine in a short burst to slow its speed to 4.96 miles per second. What must it do next?
Slow its speed again by a bit when its distance from the Earth stops decreasing.
Kuiper Belt objects are usually made of Choices
ice and possibly frozen gas
The density of rock is about 3000kg/m³. The densities of the Jovian planets are
less than 3000kg/m³ because they are mostly gas.
One way to change the course of an asteroid is to place a `mass driver' on it. The mass driver is really just a catapult that throws things (like rocks for example) away from the asteroid. The force that acts on the combined object (mass driver plus asteroid) is actually exerted by
the rocks that the catapult throws
Asteroids are
usually found in.the asteroid belt, between the orbits of Mars and Jupiter
An ion rocket engine produces 100 Newtons of thrust. What acceleration can it give to a space probe with a mass of 10,000kg?
0.01 m/s².
A solar sail is a large sheet of light-reflecting plastic spread on an extremely low-mass framework and attached to a spacecraft. Sunlight exerts a force on the sail and moves the spacecraft. Suppose the spacecraft has a total mass of 100kg (including the sail) and sunlight exerts a total force of 2N on the sail. What will be the acceleration of the spacecraft?
0.02m/s^2
Suppose that you lift an object by exerting an upward force of 22 Newtons on it. If gravity exerts a force of 10 Newtons downward on the object, what is the total force on the object?
12 Newtons
If the planets are numbered from 1 to 8, going outward from the Sun, the planet Earth is number
2
If the planets are numbered from 1 to 8, going outward from the Sun, the planet Mars is number
4
The density of water is 1000kg/m³, the density of rock is about 3000kg/m³, and the density of iron is 7800kg/m³. Which of the following densities would indicate an object that might consist of rock surrounding an iron core?
4000kg/m³
The International Space Station (ISS) is in a roughly circular orbit near the surface of the Earth, moving at around 5 miles per second. Suppose that it is desired to raise it to a new circular orbit, farther from the surface by having a rocket give it one or more short boosts. Which of the following schemes will work?
Increase its speed to 6 miles per second to put it on a rising path and give it another speed boost when its distance from the Earth stops increasing.
A planet with a large system of moons would have to be a
Jovian planet
When an arrow is fired from a bow, the arrow keeps moving after it leaves the bow because
No force stops it
When Galileo dropped a wooden ball and a heavier iron ball at the same time, he found that
Sometimes the wooden ball hit first and sometimes the iron one hit first.
Compare the magnitude of the acceleration of Earth's Moon to the acceleration of falling objects on the surface of the Earth.
The Moon's acceleration is smaller
Why couldn't we just fly a Space Shuttle to the Moon for at least a fly-by?
The Space Shuttle did not have enough fuel to reach escape velocity.
Why don't we just shoot all of our really nasty waste products into the Sun where they could not possibly bother anyone?
The Sun is actually the hardest part of the Solar System to get to from here.
A horse is pulling a cart along a road. Which of the following pairs of forces is an action-reaction pair?
The force of horse on the road and the force of the road on the horse
You are standing in an elevator that is accelerating upward at 1m/s². Which of the following pairs of forces is an action-reaction pair that has to be exactly equal and opposite to each other?
The force that the floor of the elevator exerts on you and the force that you exert on the floor of the elevator.
The Law of Inertia says that if an object is not acted on by any outside force, its acceleration
Will always be zero
Once its rockets have ceased firing, an Intercontinental Ballistic Missile will follow a path that is best described as
an ellipse with the center of the Earth at one focus.
Suppose that you drop two objects from the same height at the same time. Both objects are heavy enough to be unaffected by air resistance. If one object is twice as heavy as the other, Galileo predicted that
both objects would hit the ground at the same time
Which of the following objects would be most likely to have a long elliptical orbit that takes it from far outside the orbit of Mars to a close approach to the Sun?
comet
Most Kuiper Belt objects can best be described as
dirty snowballs or possibly flying icebergs
Most comets can best be described as
dirty snowballs or possibly flying icebergs
The density of rock is about 3000kg/m³. The density of the Earth is
greater than 3000kg/m³ because the Earth has an iron core.
If the acceleration of an object is zero, its speed
is not changing
According to Newton's Law of Gravity, the gravitational attraction of the Earth for other objects, such as the Moon, apples on trees and space shuttles in low earth orbit,
is smaller for objects farther from the Earth but never vanishes entirely.
An artificial satellite such as the International Space Station stays up because
it falls below a straight-line path in exactly the same way that the curved surface of the Earth does.
Galileo said that a moving object with nothing pushing or pulling on it will always
keep moving at the same speed
Asteroids can be made of
rock and possibly iron
Aristotle said that a moving earthly or 'mundane' object with nothing pushing or pulling on it will always
slow down and stop
Aristotle said that the amount of force on a moving earthly object determines its
speed
In Newton's Theory of planetary motion,
the Sun and Earth move around each other.
An astronomical unit is defined to be
the average distance from Earth to the Sun
The recoil or 'kick' of a gun that is firing a bullet is a force exerted on the gun by
the bullet
According to Galileo, a thrown spear keeps moving after it has left the spear throwers hand because
the force of friction with the air is not enough to stop the spear
If you are told that a 20 kilogram object is raised by 10 meters, you know that
the force of gravity on the object is 20 Newtons
If you are told that an object that weighs 20 Newtons is raised a distance of 10 meters, you know that
the force of gravity on the object is 20 Newtons
Suppose that an object with a mass of one kilogram and an object with a mass of two kilograms are both in free fall near the Earth's surface. As compared to the one kilogram object, the two kilogram object accelerates
the same because gravity pulls on it more strongly and it has more inertia
A planet that is following Kepler's Laws, accelerates
toward the Sun
When Newton calculated the magnitude and direction of the acceleration for a planet that was following Kepler's Laws, he found that the direction of the acceleration was
toward the Sun.
If an object is moving at constant speed in a straight line, its acceleration is
zero
