Gravitation Flashcards

1
Q

What is gravitational field strength?

A

The gravitational force acting on a unit mass.

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2
Q

What are reference frames that are not accelerating called?

A

Inertial reference frames

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3
Q

What is inertia?

A

A property that resists change in motion

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4
Q

In inertial reference frames a measurement is usually converted into a measurement in another by?

A

A Lorentz transformation

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5
Q

When a frame of reference is accelerating we refer to it as…

A

A Non-inertial reference frame

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6
Q

What is the equivalence principle?

A

The effect due to a gravitational field and acceleration at an equivalent rate are identical.

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7
Q

For whom (person A or B) will time “move slower” for A is in a penthouse and B is in a basement

A

B as they are “closer” to an engine, aka the center of the earth.

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8
Q

As a spaceship accelerates what happens to light?

A

It takes longer and longer for the light to travel from one end of the ship to the other.

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9
Q

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?

A

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.

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10
Q

What does acceleration and gravitational fields both do to a moving clock?

A

Make it run slow

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11
Q

Where on earth does time pass slowest?

A

The closer you are to the surface.

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12
Q

What varies with the distance from the center of the earth?

A

Gravitational field strength

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13
Q

What would be noticeably different if relativistic effects weren’t taken into account?

A

GPS and sat nav speeds/ times to get to locations

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14
Q

What happens when an object falls into a black hole?

A

It accelerates

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15
Q

The closer you get to the black hole the greater the?

A

Acceleration

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16
Q

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…

A

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

17
Q

What is the limit to escape velocity?

A

The speed of light

18
Q

What is the Schwartzchild radius?

A

The event horizon - Measures the area around an object from which light cannot escape

19
Q

What is an astronomical unit? (AU)

A

Measure of distance, is the distance between the earth and the sun (150X10^9m)

20
Q

What speed do you have to be travelling at the escape the gravitational pull at the event horizon?

A

The speed of light