Gravitational And Electrical Fields

Question 1

What is a force field?

Answer 1

A region in which a body experiences a non-contact force

Question 2

What is newtons law of gravitation?

Answer 2

The force between 2 masses is proportional to the product of the 2 masses. The force is inversely proportional to the distance between their centres squared. The force is always attractive

Question 3

What is the inverse square law?

Answer 3

If the distance between 2 objects halves, the effect of the force quadruples

Question 4

What do gravitational filed lines show?

Answer 4

They show the direction and relative magnitude of the force a mass at that point will feel

Question 5

What is gravitational field strength?

Answer 5

The force felt by a 1kg mass at that point in the field

Question 6

What is gravitational potential?

Answer 6

The work done per unit mass in moving a mass from infinity to a point (always negative)

Question 7

Why is gravitational potential always negative?

Answer 7

Gravitational potential is defined as 0 at infinity, and work must be done on a mass to move it from a point in the field to infinity, therefore potential is negative

Question 8

What is an equipotential line?

Answer 8

Points where the potential is the same, these lines are always at right angles to the field lines

Question 9

What is given by the gradient of a graph of potential against distance?

Answer 9

Field strength (need a tangent)

Question 10

What is given by the area under a graph of field strength against distance?

Answer 10

Potential difference

Question 11

What is meant by escape velocity?

Answer 11

The minimum speed an unpowered object needs in order to leave the gravitational field of a planet

Question 12

What is a geostationary orbit?

Answer 12

An orbit which has the same orbital period as the earth, and remains at the same point on the earths surface

Question 13

State the ratio of the radius of the earth to the moon

Answer 13

3.6-3.7

Question 14

State the radius of GEO

Answer 14

42000 km

Question 15

State the height of GEO

Answer 15

36000 km

Question 16

What is Coulomb’s law?

Answer 16

• the force between 2 charges is proportional to the product of the charges
• the force is inversely proportional to the distance between their centres squared
• force can be attractive or repulsive

Question 17

What do electric field lines show?

Answer 17

They show the direction and relative magnitude of the force of a positive charge at the point will feel

Question 18

Fora charged particle entering a uniform electric field at right angles, what shape does the path follow?

Answer 18

Parabolic

Question 19

What is electric potential?

Answer 19

The work done per unit charge in moving a positive charge from infinity to the point (always positive if negative charge creating the field, and always negative is positive charge creating the field)

Question 20

What does it mean when field lines are converging in a uniform field?

Answer 20

There is a stronger point in the field

Question 21

What can air be treated as when using Coulomb’s law?

Answer 21

A vacuum