Force Fields Flashcards
What is a field
A space in which one object exerts a force on another object without touching it.
At what distance does the moon stay in an orbit around the earth and why ?
At around 400 000 km because of the earths gravitational pull.
What objects create a gravitational field around them
All masses create a gravitational field around them
How would you represent the earths gravitational field by drawing
- earth in the centre
- straight lines drawn around earth (not touching)
- arrows on lines pointing towards earth to show direction
What do the arrows on a diagram of the earths gravitational field represent
The direction of the gravitational force on the objects placed in the field
What does the spacing of the lines in a diagram of the earths gravitational field represent
The strength of the gravitational field
What happens to gravitational force as we move away from the earth
It gets weaker
What happens to gravitational force as we love away from the earth
It gets weaker
What happens to gravitational force as we move away from the earth
It gets weaker
Why do we say the earths gravitational field is radial
the lines diverge racially from the centre of the Earth
What is Newton’s third law of motion
Two particles interact with each other and therefore exert equal forces on each other
What is Newtons law of universal gravitation
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
What is newtons law of gravitation in formula form
F = G (m1m2)/r^2
Nb! Everything is in SI units
What is G known as
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
What is the relationship between F and m1 in Newton’s Law of Universal Gravitation formula
F is directly proportional to m1
What is the relationship between F and m2 in Newton’s Law of Universal Gravitation formula
F is directly proportional to m2
What is the relationship between F and 1/r^2 in Newton’s Law of Universal Gravitation formula
F is directly proportional to 1/r^2
What is a gravitational field
The force acting per unit mass
What is weight (Fg)
the gravitational force the Earth exerts on any object on or near its surface
What is the weight of an object m by means of calculation
Fg=mg
What is the value of the gravitational field g near the earths surface
9,8m.s^-1
What are the three formulas to find the gravitational force between the object of mass m and the Earth
F = GMem/r^2
mg = GMem/r
g = GMe/r^2
Where Me is the mass of the earth
How do we calculate the acceleration due to gravity on any planet using the equation
g = G Mplanet / (Rplanet)^2
What happens to field strength as distance increases
it decreases as the distance R increases
What is an electric field
that region around a charged object in which another charged object will experience a
force
What determines the direction of an electric field at a point
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.
What are the two types of electric charge
Positive and negative
What will happen if like charges are brought near each other
They will repel
What will happen if unlike charges are brought near each other
They will attract
What is charge measured in
Coloumb (C)
What is coloumbs law
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
What is a point charge
a charged particle with insignificant size and mass, which carries an electric charge.
When will a point charge experience an electrostatic force
When it is brought near another point charge
What is the relationship between the electrostatic force F and q1 and q2 in coloumbs law
F is directly proportional to q1 and q2
What is the relationship between the electrostatic force F and r^2 in coloumbs law
F is inversely proportional to r^2
What happens to the size of electrostatic force F when the magnitude of the charges increases
F increases
What happens to electrostatic force F when the distance between the charges increases
F decreases
Is electrostatic force a force of attraction or repulsion
It can be either, you need to look if the charges mentioned are like charges (repel) or opposite charges (attract)
What is the formula to calculate electrostatic force
F = kq1q2/r^2
What is k in the formula to calculate electrostatic force
where k is Coulomb’s constant = 9,0 x 10^9 N·m^2·C^-2
What Is used to determine if there is an electric field in a certain region
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.
What is the magnitude of the electric field at a point
The force per unit charge
What are other names for the magnitude of an electric field
It can also be called The electric field strength or the electric field intensity
What type of quantity is Force
A vector quantity and thus it should always have magnitude and direction !!!
What formula is used to calculate the magnitude of an electric field
E = F/q
Nb! q is charge experiencing electric field
What is the direction of an electric field
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.
What is another formula to calculate the magnitude of an electric field
E = kQ/ r^2
Nb! Q is charge responsible for electric field
How do we calculate the resultant electric field for two charges
A vector sum of the two fields is calculated
What are electric field lines
These are imaginary lines that will indicate direction and magnitude of the field
What are the properties of electric field lines (6)
◦ 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
What is electric field intensity measured in
N.C^-1
What does a positive answer indicate for electric field intensity
A direction away from the charge
