Astronomy- Test #2 (ch. 5-8)

Galileo said that a moving object with nothing pushing or pulling on it will always

keep moving at the same speed.

Jovian Planets

Jupiter, Saturn, Uranus, Neptune - far from the sun

The distance from the Earth to the Sun is

one astronomical unit

In Newton's Theory of planetary motion,

the Earth moves around the unmoving Sun.

If you are told that a 20 kilogram object is raised by 10 meters, you know that

the mass of the object is 20 kilograms.

Acceleration is defined as

the rate of increase of speed

The density of water is 1000kg/m³ while the density of iron is 7800kg/m³. Which of the following values is a plausible value for the density of a terrestrial planet?

5000kg/m³

An ion rocket engine produces 1 Newton of thrust. What acceleration can it give to a space probe with a mass of 1000kg?

0.001 m/s².

Suppose that you lift an object by exerting an upward force of 12 Newtons on it. If gravity exerts a force of 10 Newtons downward on the object, what is the total force on the object?

2 Newtons.

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

What total force will cause an object with a mass of 1kg to gain 5 meters per second every second?

5 Newtons.

What total force will cause an object with a mass of 5kg to gain 10 meters per second every second?

50 Newtons

How did Aristotle's idea differ from Galileo?

Aristotle- speed (air that was in the front was going to the back) Galileo- acceleration

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, sliightly 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?

Boost its speed a bit when its distance from the Earth stops decreasing

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 and one object is twice as heavy. Who predicted that both objects would hit the ground at the same time?

Galileo.

Terrestrial planets

Mercury, Venus, Earth, Mars - close to the sun

Which of these sequences places the inner planets in the correct order from the Sun, from the closest to the farthest?

Mercury, Venus, Earth, Mars (farthest)

Which of the following statements about the moons of terrestrial planets is currently accepted?

Moons typically form near them.

Which of these planets is the farthest from the Sun?

Neptune

who discovered law of inertia? and what did it say?

Newton, a object at rest stay at rest, object in motion stay in motion unless a outside force stops it

When Newton calculated the magnitude of the acceleration of Earth's Moon, and compared it to the acceleration of falling objects on the surface of the Earth, he found that

The Moon's acceleration was 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 book, weighing 10 Newtons, sits on a table. Which of the following pairs of forces is an action-reaction pair?

The force that the book exerts on the table and the force that the table exerts on the book.

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

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

Asteroids are usually found in the asteroid belt, which is

between the orbits of Mars and Jupiter.

Comets usually follow orbits which are

elliptical with aphelia far outside the orbit of Mars.

Circular low-earth-orbit

exactly 5 miles per sec, object moves fast enough that the earth curves out from under it as it falls (artificial earth satellite)

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 a rocket pushes it and quickly increases its speed to 6 miles per second. The ISS will then

follow an ellipse that rises and then descends again.

Freely falling objects with different masses fall with the same acceleration because

gravity exerts more force on the more massive object.

Escape trajectories

greater than 7 miles per sec, -never return to the earth

Kuiper Belt objects are usually made of

ice and possibly frozen gas.

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

Suborbital Flight

object moving near the earth's surface at less than 5 miles per sec, the path is a ellipse that passes threw the earth

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.

When Galileo dropped a wooden ball and a heavier iron ball at the same time, he found that

sometimes the wooden ball hit first, sometimes the iron one hit first

An artificial satellite such as the International Space Station stays up because

the Earth curves out from under it as fast as it falls.

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 catapult that throws the rocks.

The force that acts on a rocket because its engine is firing is exerted by

the exhaust from the rocket.

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 twice as strongly and it has twice the inertia

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.

transfer orbit

velocity more then 5 less than 2 miles per sec, -ellipse shape -further from earth: slows down -closer to earth: speeds up

The Law of Inertia says that if an object is not acted on by any outside force, its acceleration

will always be zero