Gravitation Flashcards
What is gravitational field strength?
The gravitational force acting on a unit mass.
What are reference frames that are not accelerating called?
Inertial reference frames
What is inertia?
A property that resists change in motion
In inertial reference frames a measurement is usually converted into a measurement in another by?
A Lorentz transformation
When a frame of reference is accelerating we refer to it as…
A Non-inertial reference frame
What is the equivalence principle?
The effect due to a gravitational field and acceleration at an equivalent rate are identical.
For whom (person A or B) will time “move slower” for A is in a penthouse and B is in a basement
B as they are “closer” to an engine, aka the center of the earth.
As a spaceship accelerates what happens to light?
It takes longer and longer for the light to travel from one end of the ship to the other.
Person A stands at the ‘rear’ of a spaceship and Person B at the ‘front’ Person A has a torch and is sending a flash of light every second to person B. How does each person’s clock look to each other? How about if they swap over?
As the light takes longer to reach B from A as the ship accelerates. Person B sees A’s clock as running slow.
Once they swap, B now sends a flash to A every second (according to their watch) to A, then A will see the interval between the flashes of light getting smaller. A will see B’s clock as running fast.
What does acceleration and gravitational fields both do to a moving clock?
Make it run slow
Where on earth does time pass slowest?
The closer you are to the surface.
What varies with the distance from the center of the earth?
Gravitational field strength
What would be noticeably different if relativistic effects weren’t taken into account?
GPS and sat nav speeds/ times to get to locations
What happens when an object falls into a black hole?
It accelerates
The closer you get to the black hole the greater the?
Acceleration
What does it mean when an object has effectively reached infinity in our measure of the gravitational potential and has gained enough gravitational potential energy to also be at…
Zero
The minimum velocity needed is when the kinetic energy of the object after it has left the earth’s gravitational pull is zero.
Ep+Ek=0
What is the limit to escape velocity?
The speed of light
What is the Schwartzchild radius?
The event horizon - Measures the area around an object from which light cannot escape
What is an astronomical unit? (AU)
Measure of distance, is the distance between the earth and the sun (150X10^9m)
What speed do you have to be travelling at the escape the gravitational pull at the event horizon?
The speed of light
