C1 Gravitational force, Newton's Law of universal gravitational, Gravitational Fields and Gravitational potential

Gravitational Force
-Among the four fundamental forces(strong, weak, electro-magnetic and gravitational) gravity is the weakest but it has infinite range.
-Gravitational force causes objects to fall and causes planets to orbit the su, stars to orbit the centre of galaxy and galaxies to cluster together
-The concept of gravitational force was first defined by Sir Isaac Newton.
Newton's Law of universal gravitational
-Every particle in the universe attracts every other particle with a force along a line joining them.
-The force is directly proportional to the product of their masses and inversely proportional to the square of the distance between them
F=Gm[1]m[2]/r² Where; G=6.6710^-11
Centripetal acceleration img exp and eq:
F[G]=W=mg
F[G]=GMm/r^2=mg
g=GM/r^2, m=mass of earth, r=radius of earth
Gravitational Fields
-A region of space where a mass experiences a force due to the gravitational attraction of another mass.
-Gravitational field strength is defined as the gravitational force per unit mass
-Gravitational field strength gived by; g=F/m
g=GM/r² The unit of gravitational field strength: Nkg^-1
-The gravitational field lines around a point mass are radically inwards
field potential lines img:
-The gravitational field lines of a uniform field, where the field strength is the same at all points, is represented by equally spaced parallel lines. earth surface img:
Gravitational potential
-The work done per unit mass in bringing a test mass from infinity to a defined point in the field
Gravitational potential & Field strength
g=dv/dr=d(-Gm/r)/dr=-GM(-1/r^2)=GM/r2
Force F[G]=Gm[1]m[2]/r² F[E]=kq[1]q[2]/r²
-m-r-> -/q-r->
Potential V[G]=-GM/r V=kq/r
-/r-> -/r->
g=GM/r² E=kq/r²