Force Fields

Question 1

What is a field

Answer 1

A space in which one object exerts a force on another object without touching it.

Question 2

At what distance does the moon stay in an orbit around the earth and why ?

Answer 2

At around 400 000 km because of the earths gravitational pull.

Question 3

What objects create a gravitational field around them

Answer 3

All masses create a gravitational field around them

Question 4

How would you represent the earths gravitational field by drawing

Answer 4

• earth in the centre
• straight lines drawn around earth (not touching)
• arrows on lines pointing towards earth to show direction

Question 5

What do the arrows on a diagram of the earths gravitational field represent

Answer 5

The direction of the gravitational force on the objects placed in the field

Question 6

What does the spacing of the lines in a diagram of the earths gravitational field represent

Answer 6

The strength of the gravitational field

Question 7

What happens to gravitational force as we move away from the earth

Answer 7

It gets weaker

Question 8

What happens to gravitational force as we love away from the earth

Answer 8

It gets weaker

Question 9

What happens to gravitational force as we move away from the earth

Answer 9

It gets weaker

Question 10

Why do we say the earths gravitational field is radial

Answer 10

the lines diverge racially from the centre of the Earth

Question 11

What is Newton’s third law of motion

Answer 11

Two particles interact with each other and therefore exert equal forces on each other

Question 12

What is Newtons law of universal gravitation

Answer 12

Every particle in the universe attracts every other particle with a force which is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centres

Question 13

What is newtons law of gravitation in formula form

Answer 13

F = G (m1m2)/r^2
Nb! Everything is in SI units

Question 14

What is G known as

Answer 14

The universal gravitational constant that sets the strength of the gravitational interaction in the sense that if it were doubled, so would all the gravitational forces be doubled. G=6,7 x 10^-11 Nm^2.kg^-2

Question 15

What is the relationship between F and m1 in Newton’s Law of Universal Gravitation formula

Answer 15

F is directly proportional to m1

Question 16

What is the relationship between F and m2 in Newton’s Law of Universal Gravitation formula

Answer 16

F is directly proportional to m2

Question 17

What is the relationship between F and 1/r^2 in Newton’s Law of Universal Gravitation formula

Answer 17

F is directly proportional to 1/r^2

Question 18

What is a gravitational field

Answer 18

The force acting per unit mass

Question 19

What is weight (Fg)

Answer 19

the gravitational force the Earth exerts on any object on or near its surface

Question 20

What is the weight of an object m by means of calculation

Answer 20

Fg=mg

Question 21

What is the value of the gravitational field g near the earths surface

Answer 21

9,8m.s^-1

Question 22

What are the three formulas to find the gravitational force between the object of mass m and the Earth

Answer 22

F = GMem/r^2

mg = GMem/r

g = GMe/r^2

Where Me is the mass of the earth

Question 23

How do we calculate the acceleration due to gravity on any planet using the equation

Answer 23

g = G Mplanet / (Rplanet)^2

Question 24

What happens to field strength as distance increases

Answer 24

it decreases as the distance R increases

Question 25

What is an electric field

Answer 25

that region around a charged object in which another charged object will experience a
force

Question 26

What determines the direction of an electric field at a point

Answer 26

The direction of an electric field at a point is the direction in which a small positive charge would move
(under the influence of the field) if placed at that point.

Question 27

What are the two types of electric charge

Answer 27

Positive and negative

Question 28

What will happen if like charges are brought near each other

Answer 28

They will repel

Question 29

What will happen if unlike charges are brought near each other

Answer 29

They will attract

Question 30

What is charge measured in

Answer 30

Coloumb (C)

Question 31

What is coloumbs law

Answer 31

Two point charges in free space or air exert forces on each other. The force is directly proportional to the product of the charges and inversely proportional to the square of the distance between the charges

Question 32

What is a point charge

Answer 32

a charged particle with insignificant size and mass, which carries an electric charge.

Question 33

When will a point charge experience an electrostatic force

Answer 33

When it is brought near another point charge

Question 34

What is the relationship between the electrostatic force F and q1 and q2 in coloumbs law

Answer 34

F is directly proportional to q1 and q2

Question 35

What is the relationship between the electrostatic force F and r^2 in coloumbs law

Answer 35

F is inversely proportional to r^2

Question 36

What happens to the size of electrostatic force F when the magnitude of the charges increases

Answer 36

F increases

Question 37

What happens to electrostatic force F when the distance between the charges increases

Answer 37

F decreases

Question 38

Is electrostatic force a force of attraction or repulsion

Answer 38

It can be either, you need to look if the charges mentioned are like charges (repel) or opposite charges (attract)

Question 39

What is the formula to calculate electrostatic force

Answer 39

F = kq1q2/r^2

Question 40

What is k in the formula to calculate electrostatic force

Answer 40

where k is Coulomb’s constant = 9,0 x 10^9 N·m^2·C^-2

Question 41

What Is used to determine if there is an electric field in a certain region

Answer 41

A small charged particle is placed in the region.

◦ If the test charge experiences a force there is an electric field in the region.
◦ The direction of the electric field is always the direction in which a positive point test charge
moves.
◦ Field lines move from positive to negative.

Question 42

What is the magnitude of the electric field at a point

Answer 42

The force per unit charge

Question 43

What are other names for the magnitude of an electric field

Answer 43

It can also be called The electric field strength or the electric field intensity

Question 44

What type of quantity is Force

Answer 44

A vector quantity and thus it should always have magnitude and direction !!!

Question 45

What formula is used to calculate the magnitude of an electric field

Answer 45

E = F/q

Nb! q is charge experiencing electric field

Question 46

What is the direction of an electric field

Answer 46

The direction of force acting on a positive test charge is taken as the direction of the electric field intensity at any point in the field. The electric field radiates outwards from a positive point charge.

Question 47

What is another formula to calculate the magnitude of an electric field

Answer 47

E = kQ/ r^2

Nb! Q is charge responsible for electric field

Question 48

How do we calculate the resultant electric field for two charges

Answer 48

A vector sum of the two fields is calculated

Question 49

What are electric field lines

Answer 49

These are imaginary lines that will indicate direction and magnitude of the field

Question 50

What are the properties of electric field lines (6)

Answer 50

◦ They are imaginary
◦ They are solid lines
◦ The never cross each other
◦ always form a 90 degree angle with the object it originates from
◦ Will point away from a positive charge and towards a negative charge
◦ The density of the lines indicate the field strength

Question 51

What is electric field intensity measured in

Answer 51

N.C^-1

Question 52

What does a positive answer indicate for electric field intensity

Answer 52

A direction away from the charge