Gravitational fields Flashcards
how do you find the acceleration due to gravity
measure mass
measure reading on newtonmeter
f=ma
graph should intercept origin
force on y mass on x gradient should be acceleration
what is the value for G
G = 6.67 x10^-11 m^3kg^-1s^-2
when would you not uses Egp = Ke
When there is a big change of height due to the effect of gravity is different the further away you are
whats the Force (w) equation
Fw = - Gmamb
————-
r^2
equation for effect due to gravity
follows the inverse square law
g=Gm
——
r^2
Definition for Gravitational Potential
V is the GPE per unit mass in a gravitational field
V = Egp
——
m
Therefore the Gravitaional potential at a position in a field caused by mass B would be
Vb = - Gmb
———
r
simplified potential equation
V = - Gm
——–
r
What equation relates Gravitational Potential and velocity
V1 - V2 = 1/2 x v^2
simularities of gravitational fields and electric fields
- both fields follow the inverse square law
2.both can be radial and uniform fields - inversely proportional to the distance away(r)
Differences of Gravitational fields and electrical fields
1.Gravitational fields only cause attraction where as electric fields both attract and repel
2.gravitational fields only act on objects with mass where as electric fields only act on charged particles
3.Gravitational potential is always negative where as electric potential can be either positive or negative
what is keplers Third Law
The square of an orbiterd period, T, is proportional to the cube of its seperation from what is orbiting , r.
It is also stated that the quare of the period, T, is inversely proportional to the mass being orbited
equations for centripetal forces
f = mv^2
——-
r
f = gmamb
———-
r^2
velocity in terms of mass
Gm
—— = v^2
r
