[emdiesse]

I thought I would start this thread up and put a load of formulas down that you may find useful, I don't know which ones are given you you in the exam or not so Iit would also help if someone could clarify. However, my main motive for making this thread is that it will hopefully give me one last chance at making sure the formula I know are correct and feel good that I may be helping other people in the process. You may want to dot he same and post your knowledge.

Here goes.

Forces in Physics
Gravity Forces
F = mg [Weight of a mass m near an object of gravity g]
g = (-)GM/r² [The value of g at a distance r from the centre of a planet of mass M (the minus is the magnitude)]
F = GMm/r² [The force of G between mass m and mass M]

Electrostatic Forces
E = v/d The electric field strength between two charged parallel plates
F = qV/d The force on a charge q between two charged parallel plates
E = kQ/r² The electric field near a point or spherical charge
F = KQq/r² The force on a charge q near a point or spherical charge

Magnetic Forces
F = BIl The force on a current flowing at 90degrees to a magnetic flux density B
F = Bqv The force on a charge q moving at velocity v at 90degrees to a magnetic flux density B

Others
F = kx the force produced by a stretched spring or piece of material
F = -ks the force on an oscillator that is moving with simple harmonic motion

Force and Motion Relationships
F = ma Force, acceleration and mass
Ft = Δp Impulse and momentum
E = FD Forces and energy

Energy in physics
Gravitational PE
PE = mgh The potential energy of a mass m lifted a hieght h above the earth
Vg = -GM/r The value of gravitational potential energy at a distance r from the centre of mass M
PE = -GMm/r The PE of mass m and mass M at a distance r apart

Electrostatic PE
E = qV The PE lost when a charge q moves through potential difference V
E = ½*CV² The PE stored in a charged capacitor
V = kQ/r The electrical potential V near a point or spherical charge
PE = kQq/r The PE of a charge q near a point or spherical charge Q

Others
E = ½*kx² The energy stored in a stretched spring or piece of material
KE = ½*mv² The kinetic energy of a moving mass m
E = ½*ka² The energy of a simple harmonic oscillator with amplitude A
E = hf Photon energy
E = mCΔθ The energy needed to change the temerature of a material
E = kT The average energy of a particle at temperature T

Time Speed and Distance
Time formulae
t = s/v Time to go distance s at constant velocity v
t = 2π√(m/k) Period of oscillation (mass on a spring)
t = 2π√(l/g) Period of oscillation (Pendulum)
t = ln2/λ Formula for radioactive half-life
t = 0.69RC Time for charge in a capacitor to half
t = RC Time for capacitor's charge to fall by 37%
t = 1/f The relationship between period and frequency
t = E/P The relationship between power time and energy

Laws
Keplers 3rd Law t² = r³

Correct me if i'm wrong
It might be useful if messages reporting errors are written in red and quote the wrong and state the right in green.

Add stuff please

[Stevenius]

Thanks so much for doing all that, its really helpful to have all teh formulas in one place and with explanations of what they are actually for!

[emdiesse]

Is anyone able to tell me the formula for

Time to go distance s at a constant acceleration a
Time round a circular orbit at a constant speed
Time for universe to expand

[ridgey1988]

Originally Posted by emdiesse

Is anyone able to tell me the formula for

Time to go distance s at a constant acceleration a
The SUVAT equations??
or just v-u = at

Time round a circular orbit at a constant speed
um sorta.
F= omega(lowercase)^2 x radius x mass
F also = mv / t
i think! off the top of my head. but i think you would need more than one equation!!.

Time for universe to expand

the hubble constant!! Hzero. i think its about 10^-15 years. not sure tho.

sorry if this is unhelpful.......i would go get my book and look it up for you. but its downstairs and im lazy :P

[ridgey1988]

ha!! i dont mean -15 ...that would be silly. im just over enthusiastic with minuses.

[emdiesse]

Thanks

10^-15 years! Wow, i'm older than the universe I'm also over enthusiastic with them. It doesn't help in exams!

[TomX]

Keplars law should be:
t^2 \proportional r^3

[Ourkid]

Originally Posted by emdiesse

I thought I would start this thread up and put a load of formulas down that you may find useful, I don't know which ones are given you you in the exam or not so Iit would also help if someone could clarify. However, my main motive for making this thread is that it will hopefully give me one last chance at making sure the formula I know are correct and feel good that I may be helping other people in the process. You may want to dot he same and post your knowledge.

Here goes.

Forces in Physics
Gravity Forces
F = mg [Weight of a mass m near an object of gravity g]
g = (-)GM/r² [The value of g at a distance r from the centre of a planet of mass M (the minus is the magnitude)]
F = GMm/r² [The force of G between mass m and mass M]

Electrostatic Forces
E = v/d The electric field strength between two charged parallel plates
F = qV/d The force on a charge q between two charged parallel plates
E = kQ/r² The electric field near a point or spherical charge
F = KQq/r² The force on a charge q near a point or spherical charge

Magnetic Forces
F = BIl The force on a current flowing at 90degrees to a magnetic flux density B
F = Bqv The force on a charge q moving at velocity v at 90degrees to a magnetic flux density B

Others
F = kx the force produced by a stretched spring or piece of material
F = -ks the force on an oscillator that is moving with simple harmonic motion

Force and Motion Relationships
F = ma Force, acceleration and mass
Ft = Δp Impulse and momentum
E = FD Forces and energy

Energy in physics
Gravitational PE
PE = mgh The potential energy of a mass m lifted a hieght h above the earth
Vg = -GM/r The value of gravitational potential energy at a distance r from the centre of mass M
PE = -GMm/r The PE of mass m and mass M at a distance r apart

Electrostatic PE
E = qV The PE lost when a charge q moves through potential difference V
E = ½*CV² The PE stored in a charged capacitor
V = kQ/r The electrical potential V near a point or spherical charge
PE = kQq/r The PE of a charge q near a point or spherical charge Q


Others
E = ½*kx² The energy stored in a stretched spring or piece of material
KE = ½*mv² The kinetic energy of a moving mass m
E = ½*ka² The energy of a simple harmonic oscillator with amplitude A
E = hf Photon energy
E = mCΔθ The energy needed to change the temerature of a material
E = kT The average energy of a particle at temperature T

Time Speed and Distance
Time formulae
t = s/v Time to go distance s at constant velocity v
t = 2π√(m/k) Period of oscillation (mass on a spring)
t = 2π√(l/g) Period of oscillation (Pendulum)
t = ln2/λ Formula for radioactive half-life
t = 0.69RC Time for charge in a capacitor to half
t = RC Time for capacitor's charge to fall by 37%
t = 1/f The relationship between period and frequency
t = E/P The relationship between power time and energy

Laws
Keplers 3rd Law t² = r³

the one in red, is that meant to be gravitational potential? because if it is, then it should be V = -GM/r, and if its meant to be gravitational field strength then its g=GM/r^2

[emdiesse]

Originally Posted by w00tt

the one in red, is that meant to be gravitational potential? because if it is, then it should be V = -GM/r, and if its meant to be gravitational field strength then its g=GM/r^2

Its supposed to be gravitational potential

[Ourkid]

anyone rekon we'll need to know about parsecs and parallax?

[alex2784]

I hope not, never even heard of them!