Gravitation Flashcards
objects near the surface of Earth will…
fall to the ground
pulled down with a force of 9.8N
accelerate at 9.8ms^-2 downwards
Newton’s law of gravitation
- there is a force of attraction between two objects
- size of force is proportional to the product of masses of the objects and inversely proportional to the square of the distance between them
gravitation equations
W=mg
F=Gm1m2/r squared
g=Gm/r squared
force of m1 on m2 is…
the same as m2 on m1
force between objects is bigger if…
objects have more mass/ are close together
force between objects is smaller if…
objects are far away from each other/ have less mass
gravitational field strength of a planet/ satellite depends only on…
its mass and radius
where is r measured from?
the centre of the object
terminal velocity
constant velocity (zero acceleration) because the upward force (air resistance) is equal and opposite to the weight
how high a projectile travels depends on…
vertical velocity
how far a projectile travels depends on…
horizontal velocity
describe motion of projectile if fired at a large angle
will travel high but not far
describe motion of projectile if fired at a small angle
will travel far but not high
if ball is accelerating vertically, what never changes?
horizontal velocity
what value should never be used in projectile motion questions
the diagonal velocity
must work out h and v components
how to lay out projectile questions
SUVAT down side with vertical column and horizontal column
what is vertical time equal to?
horizontal time (same object)
if from rest, what is u?
0m/s
motion equations
v=u+at
v squared=u squared + 2as
s=ut+1/2at squared
s=1/2(u+v)t
equation to use for horizontal
s=vt since it is not accelerating
what is vertical acceleration
-9.8m/s squared
vertical velocity at max height
0m/s
what is resultant velocity?
vertical and horizontal velocity added in vector triangle
what should always be stated if question asks for velocity?
direction
if a projectile is moving horizontally, what is vertical velocity?
0m/s
what is final vertical velocity if projectile takes off and lands on a level surface
equal and opposite to the initial vertical velocity
