Astro Mid Term Sem. 2 (Book 5/7)

Question 1

What was Galileo’s thoughts on Gravity?

Answer 1

He believed that all objects fall at the same speed unless air resistance or some other force acts upon them

Question 2

What is Gravity?

Answer 2

• Gravity is the attractive force that exists between 2 objects
• A property of the space in the presence of an object with mass - the GRAVITATIONAL FIELD
• In Newtonian picture, we live in a 3-dimensional space. The time from space dimensions

Question 3

What was Einsteins happiest thought?

Answer 3

“I was sitting in a chair in the patent office at Bern when all of a sudden a thought occurred to me: IF A PERSON FALLS FREELY HE WILL NOT FEEL HIS OWN WEIGHT… I was startled. This simple thought made a deep impression on me. It impelled me towards a theory of gravitation.”

• This means that gravity can be cancelled out by acceleration

Question 4

What is Einstein’s “Equivalence Principle”?

Answer 4

• In any given location, it is impossible to distinguish between the effects of accelerated motion and those of a gravitational field
• Gravity is equivalent to acceleration

Question 5

How does matter distort spacetime? (use trampoline reference) found in book 5 middle of page 2

Answer 5

• Matter distorts spacetime like weights on a taut rubber sheet
• The greater the mass, the greater the distortion of spacetime

Question 6

What is Space-Time Curvature?

Answer 6

• Einstein’s theory of General Relativity says that space-time is curved by the presence of a mass
• A mass in space causes a curvature in space fabric
• The curvature then explains the movement of the matter

Question 7

What is Gravity? (Part 2: specific to spacetime)

Answer 7

• The curvature of the spacetime continuum is produced by the presence of mass
• Massive object distorts spacetime continuum more

Question 8

Orbits can now be explained in a new way; on object will travel on AS STRAIGHT A PATH AS POSSIBLE through spacetime. TRUE or FALSE?

Answer 8

TRUE

Question 9

Orbits can now be explained in a new way; on object will travel on AS STRAIGHT A PATH AS POSSIBLE through spacetime. TRUE or FALSE?

Answer 9

TRUE

Question 10

Orbits can now be explained in a new way; on object will travel on AS STRAIGHT A PATH AS POSSIBLE through spacetime. TRUE or FALSE?

Answer 10

TRUE

Question 11

Newton’s law predicted that the orbit of Mercury should change. Why is that?

Answer 11

• due to gravitational influence of the planets
• this change was measured in the 1800’s
• BUT Newton’s law could not account for the exact change which was observed
• Einstein knew of this discrepancy and used general relativity to explain it
• Predictions of general relativity matched the observations exactly