Gravitational Fields

Question 1

What will any object with a mass experience when put in the gravitational field of another object?

Answer 1

An attractive force

Question 2

What is a gravitational field?

Answer 2

It is a region where a body experiences a force, force field

Question 3

What does an object need to have in order to experience a significant gravitational field?

Answer 3

A large mass

Question 4

What types of gravitational fields can you have?

Answer 4

Uniform

Radial, when a mass is moved further away, the force it experiences decreases

Question 5

What do gravitational field lines show?

Answer 5

The strength of the field at each point, where there is a higher density of field lines, there is a stronger field

Question 6

what happens close to the Earth’s surface?

Answer 6

Over a small local region, the force is almost uniform as the lines are nearly parallel

Question 7

Newtons law of gravitation?

Answer 7

Any two masses will attract each other with a force F, which is proportional to the product of their masses and inversely proportional to the square of the distance between them.

Question 8

What type of law is the law of gravitation?

Answer 8

It is an inverse square law so when R decreases, F increases, this is because it is radial so the force will be the same at any point at the surface.

Question 9

What is a gravitational field strength?

Answer 9

It is the gravitational force per unit mass and acts towards the centre of the mass whose field is being described, it produces the centipetal force

Question 10

What can the gravitational field strength be seen as?

Answer 10

The acceleration of the mass due to gravity or in an gravitational field

Question 11

What type of gravitational fields do point masses have?

Answer 11

Radial

Question 12

What type of law is radial gravitational fields part of?

Answer 12

It is the inverse square law because as R doubles, G decreases to a quarter of its original value

Question 13

Are gravitational fields vectors or scalar?

Answer 13

They are vectors, you can add them up to find the combined effect of more than one object by taking one direction is positive and the other is negative and adding.

Question 14

What is gravitational potential?

Answer 14

It is the gravitational potential energy that a unit mass at that point would have, it is numerically equal to the work done in taking a unit mass from infinity to that point

Question 15

What is gravitational potential at the surface of earth?

Answer 15

It is negative and then increases with distance from the earth.

Question 16

When would gravitational potential be zero?

Answer 16

At any infinite distance from the mass

Question 17

What is gravitational potential difference?

Answer 17

It is the distance needed to move a unit mass from one point to another

Question 18

What happens when you move an object?

Answer 18

There is work done against gravity

Question 19

What happens due to friction?

Answer 19

The radius of the orbit will decrease, causing the total energy to decrease which means that it is moved to a lower orbit and the velocity of the object increases

Question 20

What happens when there is a greater radius on the satellite’s orbit

Answer 20

It will travel slower and it will take longer to complete one orbit

Question 21

What is always constant for an orbiting satellite?

Answer 21

The total energy, it has both kinetic and potential energy, this is all constant because height and speed are constant for circular orbit.

Question 22

What occurs in elliptical orbits?

Answer 22

The satellite will speed up as its height decreases this means that potential energy and kinetic energy change however the total energy is always constant

Question 23

Features of a geosynchronous orbit?

Answer 23

It will orbit directly over the equator, staying in the same point relative to a certain point on earth, so will appear stationary. They travel at the same angular speed as a so are useful for TV and telephone signals as they do not have to alter the receiver to keep up with the signals. Their orbits take exactly one day.

Question 24

What are polar orbits useful for?

Answer 24

Weather satellites, as they travel around the earth multiple times each day. They could also be used for surveillance.