Test 2 Flashcards
The time for one Earth rotation
Day
The time for one Earth orbit around the sun
Year
The approximate time for the moon to orbit Earth
Month
How could people of ancient times tell the time of the year?
They built ancient structures as a calendar to aid in farming and hunting
What two ways do planets move across the sky?
- Direct Motion
2. Retrograde Motion
What is Direct Motion?
Normal eastward movement
What is Retrograde Motion?
Occasional westward movement
What did Aristotle assert about the universe?
Asserted that the universe is governed by physical laws
How did Aristotle describe the model of the universe?
The Earth is at the center of the universe
What contributions did Copernicus add to astronomy?
- Developed a mathematical modal for a sun-centered solar system
- Proposed the retrograde motion was really a result of parallax
What is the apparent motion of a body due to motion of the observer
Parallax
What contributions to astronomy did Tycho Brahe make?
He made precise measurements of the positions of the planets
What did Kepler describe about planetary orbits?
The orbit of a planet about the sun is an ellipse
What are Kepler’s three laws?
- The orbit of a planet about the sun is an ellipse with the sun at one focus
- A line joining a planet and the sun sweeps out equal areas in equal intervals of time
- The closer the planet is to the sun in its orbit, the faster it moves. The further away, the slower it moves
What happens as the planets get closer to the sun during their orbits?
They move faster
What is the average distance of the earth from the sun?
Astronomical Unit
What was Galileo the first to use?
Telescope
What were Galileo’s discoveries?
The moons of Jupiter, the moon
What is speeding up?
Acceleration
What is the gravitational constant times the product of masses divided by the square of distance between the masses?
Force
What is the energy of motion?
Kinetic Energy
What is stored energy?
Potential Energy
What is heat energy?
Thermal Energy
What are Newton’s Three Laws?
- Law on Inertia
- F=ma
- Action=Reaction
What is the Law of Inertia?
A body remains at rest or moves in a straight line at a constant speed unless acted upon by a force
What is F=ma?
The amount of acceleration that a force produces depends on the mass of the object being accelerated
What is Action=Reaction?
Whenever one body exerts a force on a second body, the second body exerts an equal and opposite force on the first body
What is the force of gravity?
F=G(mass 1 x mass 2)/ d squared
What are two ways an object can be “weightless?”
- The space shuttle and space stations are falling towards the earth
- When going to the moon the distance from the earth increases, the force of gravity decreases
What did Einstein say about the laws if physics and the observers?
They are the same for all observers, no matter what their motion, as long as they are not accelerated
How is time affected by speed?
Time “moves” slower the faster an object goes
What is a theory of cosmic evolution that tells us how the universe has evolved, how it has changed from the beginning to today?
The Big Bang
What is the energy source from the sun?
Converts 700 million tons of hydrogen into 695 million tons of helium every second. The other 5 million in converted into energy.
What is the winter and summer solstice?
The shortest and longest days of the year
What is Helocentrism?
The sun is at the center of the universe
Describe Aristotle’s model of the universe
He imagined the earth at the center of the universe
How did Copernicus change the model of the universe?
He moved the earth form the center of the universe and replaced it with the sun.
What did Kepler’s calculations show?
The planets travel in elipses around the sun
What happens as the planets approached the sun?
They speed up
Do we move or do the stars move?
We move
What does the Bible tell us?
How to get to heaven, not how the heavens go
Why is Galileo considered the first modern scientist?
He documented his observations and he proposed theories
If there was a beginning to the universe, what does that mean?
There is going to be an end
What is space-time?
A fabric that combines space and time
How does space change in the presence of gravity?
It bends/warps space-time
What question religion ask?
Why was the universe created
What question does science ask?
How was the universe created
What is the affect of gravity on light?
It bends light
What did Father Lemaitre reason about the universe?
It was born and the universe is expanding
What did Hubble say about the movement of galaxies?
They are moving away from each other. The universe is always expanding.
If everything came from Hydrogen, then where did the other elements come from?
Hydrogen fuses to form helium and helium and hydrogen fuse to form heavier elements
What are the four known forces?
- Weak Nuclear
- Strong Nuclear
- Gravity
- Electromagnetism
What happens as the sun cools?
It expands, turns red, and gets closer to earth
What is dark energy?
What we don’t see
How is dark energy formed?
It is formed at the death of stars
What is meant by we are part of the universe and the universe is part of us?
We are formed in the universe, we are made of elements that were formed by the Big Bang from star dust
