Gravitational field Flashcards
Gravitational force is always ________.
Gravitational force is always attractive
What is a force field?
A force field is a region in which a body experiences a force.
What object has gravitational fields?
only large mass have gravitational field that produce a significant effect.
what is a radial field?
The lines of force meet at the centre of the point mass
What does it mean when a field has high line density?
The higher a line density is, the stronger a gravitational field.
what happen to the field lines when it is close to earth’s surface?
the field is almost uniform - the field lines are almost parallel.
what does gravitational force depend on?
the masses and the distance between them
what is gravitational force?
F=Gm1m2/r^(2)
what is inverse square law?
F is proportional to 1/r^(2)
what happen to the force when the distance between two masses increases?
the force decreases
what happen to the force if the distance is double?
the force will be one quarter the strength of the original force
why the law of gravitation is an inverse square law?
because the gravitational field is radial
what is gravitational field strength?
g=F/m
what does gravitational field strength tell you?
it tells you how strong the force due to gravity is at any point in a gravitational field
what is the unit for g?
Nkg^(-1)
is g a vector quantity or scalar quantity?
vector and it always point towards the centre of mass of the object whose field you are describing.
what would you describe g at Earth’s surface?
it’s almost constant
radial field
g=GM/r^(2)
what is gravitational potential?
V=-GM/r
what is the unit for gravitational potential?
Jkg^(-1)
what does gravitational potential tell you?
gravitational potential is the gravitational potential energy that a unit mass would have
why is gravitational potential negative?
Gravitational potential is negative at the surface of the mass and increases with the distance from the mass
g=?
- delta V/ delta r
what is gravitational potential difference?
delta W = m delta V
what does gravitational potential difference tell you?
it’s the energy needed to move a unit mass and it depends on the mass and the gravitational potential difference you move it through
what is gravitational potential energy
Ep = mV = -GMm/r
What does gravity act like to objects in orbit?
Gravity acts as the centripetal force that keeps objects in orbit around a much larger body
What keep planets and satellites in orbit?
Gravitational force
what is the speed of satellites?
V^(2)=GM/r
what is the speed of satellites proportional to?
V is proportional to 1/r^(1/2)
What is orbital period?
T= (4pi^(2)r^(3)/GM)^(1/2)
what is the definition of orbital period?
the time taken for a satellite to make one orbit
What is orbital period proportional to?
T is proportional to (r3)^(1/2)
The greater the radius, the slower it will travel and the longer it will take to complete one orbit
When a satellite travels in a circular orbit, does the total energy change?
No, It remains constant
what forms of energy does a satellite have when it is travelling?
potential energy and kinetic energy
When a satellite travels in a circular orbit, does kinetic energy change?
No, It remains constant
When a satellite travels in a circular orbit, does potential energy change?
No, It remains constant
When a satellite travels in a elliptical orbit, does the total energy change?
No, It remains constant
When a satellite travels in a elliptical orbit, would kinetic energy change?
Yes, it increases when the potential energy decreases. in other words, it speeds up as its height decreases
When a satellite travels in a elliptical orbit, would potential energy change?
Yes, it increases when the kinetic energy decreases. It slower down as height increases.
what is a geosynchrpnous satellite?
it’s a satellite orbits directly over the equator and it’s stationary relative to a certain point on the Earth
