Gravitational field ,Satellite motion and Torques Flashcards
what is a Torque?
a turning force
a torque is applied when a force acts at a posistion othern than the centre of mass or fixed axle
Forces produce translational acceleration ,what do Torques produce?
Ratational accelartion
Torque does the same thing for rotational movement as force does for translational movement.
1.Forces causes translationalacceleration
2.Torques cause rotationalacceleration
what is the Pivot point
The axis about which the object rotates
what is a lever arm?
the distance from the pivot point to where the force is applied
what is the perpendicular distance
The shortest distance from the pivot point to the line of action
explain why a saucepan with a longer length handle would be harder to keep horizontal to avoid spilliing water compared to one with a smaller handle
The saucepan with the longer handle will be harder to keep horiontal .This is because the weight of the water is acting further away from the hand which is conisdered as the pivot point .Since distance between the pivot point and the weight force is increased the Torque is increase which makes it more likely for the saucepan to tip
what happens when the pivot point is increased
the Torque also increases
List three changes that could be made to increase the amount of TORQUE applied to an object
Increase the force applied to the handle
decreases the angle of the force
Push higher up on the handle
lesson outcomes for Gravitational field
1.all objects with mass attract one another with gravitaional forces ;The magnitude of this force can be caluculated using Newton’s Law of Universal Gravitation
2.objects with mass produce a gravitational field in space that surrounds them;Field theory attributes the Gravitational force on an object to the presence of a gravitationaal field
3.gravitational field strenght is defined as the net force per unit mass at a particular point in the field
Gravitational fields
- Fields are used in physics to represent non-contact forces
1. Electric Fields
2. magnetic fields
3. gravitational fields
all objects with mass produce a gravitational field
Gravitational field lines show;
1.direction force (using arrows)
2.Strength of force(using density of lines)
Gravitational fields on the earth
go down torwards the ground and are even spaced
Newton’s Law of Universal Gravitation
Remember for Gravitational forces
The gravitational force attracting two objects is symmetrical
the resulting acceleration is not
acceleration of Planets
What is Gravitational field strength ?
the net force per unti mass caused by the grav field=GM/r^2
It is equivalent to the acceleration that an object will undergo in that Gravitaional field
For gravitational fields questions when asked for altitude use…..
distance found -radius of the earth
(the total distance from centre to center- radius of the thing u got)
test advice
be familiar with the terminology in physics (Gravitational field strength,Garviational forc
Explain why both mass and density affect the gravitational field strength at the surface of any celestial body.
A larger mass increases the gravitationali field strength .A denser celesital body has a small radius compared to a less dense body of the same mass.A denser body therefore increases the gravitational field strength near the surface
Explain why gravitational field strength does not depend on the density of the celestial body as the altitude increases.
when applyign the grav field stregth formula the mass of the entire body and R is the distance from the centre of the body’s mass.It does not matter how dense the body is when far away from the centre .Being denser means that it’s possible to get closer to the centre cause the mass is within a smaller value
what is a geosynchronus orbits
A geosynchronus satelite has an orbital period which matches the Earth’s Rotational period (24hrs)
* useful for keeping the satelite above the same region
use kelpers law for orbital froblems and FC=Fg to derive kelps laws
How to calculate velocity of a satellite orbiting earth
V=square root of GMof earth/r
Note r= the sum of the radius of earth and the height above the earth
