FORCES Flashcards
What do vector quantities have
magnitude and a direction
examples of vector quantities
velocity
acceleration
momentum
what do scalar quantities have
magnitude
examples of scalar quantities
speed
distance
time
what is a contact force
when two objects are touching for a force to act
examples of a contact force
friction
air resistance
tension in ropes
normal contact forces
what is a non contact force
if the objects do not need to be touching for a force to act
examples of a non contact force
magnetic force
gravitational force
electrostatic force
what is gravitational force
is the force of attraction between masses
what does the weight of an object depend on
the strength of the gravitational field at the location of the object
mass and weight are …..
directly proportional
weight =
mass * gravitational field strength
increasing the mass of an object increases the ….
weight
what is resultant force
is the overall force on a point or an object
when a force moves an object through a distance what happens
energy is transferred and work is done on the object
work done =
force * distance
when all forces are balanced an object is
equilibrium
what diagram can you draw to find out resultant forces
scale drawings
extension is __________ force
directly proportional
force= (springs) units
spring constant (n/m) * extension (m)
what does spring constant depend on
the material
the stiffer the materal the greater the spring constant
what happens when a graph showing force and extension curves (spring)
it has reached its limit of proportionality
elastic potential energy =
1/2 * spring constant (n/m) * extension (m) (squared)
what is a moment
a moment is the turning effect of a force
moment of a force=
force * distance
how do you get the maximum moment
need to push at right angles
what are levers
levers increase the distance from the pivot at which the force is applied
what do levers make it easier to do
makes it easier to work
what are gears used for
they are used to transmit the rotational effect of a force from one place to another
what are different size gears used for
they can be used to change the moment of a force
pressure =
force/area
what does pressure in a liquid depend on
depth
density
the more dense a liquid is ….. which means….
the more particles in a certain space,, which means there are more particles available to collide s the pressure is higher
as the depth of liquid increases ….
the number of particles above that point increases, the weight of these particles adds to the pressure felt at that point so liquid pressure increases with depth
pressure = (depth)
height* gravitational field * density of a liquid
how does an object float
if the upthrust on an object is equal to the object weight then the forces balance and the object floats
how does an object sink
if an object weight is more than the upthrust the object sinks
what happens when an object is denser than the fluid it is placed iin
the object is unable to displace enough fluid to equal its weight this means that its weight is always larger than the upthrust so it sinks
what is distance
how far an object has moved
is distance a scalar or a vector
scalar
is displacement a scalar or a vector
vector
speed =
distance/ time
what is acceleration
acceleration is the change in velocity in a certain amount of time
average accerleration =
change in velocity/time
what is constant acceleration also called
uniform accleration
equation for uniform acceleration
v2-u2=2as final velocity-initial velocity = 2 * accerleration * distance
distance time graphs gradient=
speed
flat sections on a distance time graph =
stationary it has stopped
straight uphill sections on a distance time graphs =
travelling at a steady speed
curves represent on a dt graph
accerlerATION OR DECERLAERATION
WHAT DOES A STEEPENIGN curve represent
what does a levelling odf== curve reoprestn
speeding up
slowing down
on a vt graph gradient =
acceleration
on a vt graph flat sections represent
travelling at a steady speed
the steeper the vt graph
the greater the acceleration or deceleration
uphill sections on a vt graph are
dowbhill sections on a vt graph are
acceleration
deceleration
what deos a curve mean on a vt graph
changing acceleration
hoe do you work out distance travelled on a vt graph
calculate the area under the graph
drag increases as ….
speed increases
friction always acts in the …..
opposite direction to movement
how do objects reach terminal velocity
as the object falls it accelerates towards the earth due to the force of gravity
air resistance also acts on the object in the opposite direction to the force due to gravity
as the object speeds up the air resistance increases until the accelerating force and the air resistance balance
it has reach terminal velocity
