Please enable JavaScript.
Coggle requires JavaScript to display documents.
P5 - Forces and Motion - End of Topic - Part 2 - Coggle Diagram
P5 - Forces and Motion - End of Topic - Part 2
L17 and L18 - Newton's Laws of Motion
Newtons 1st Law
states that when an object has a
resultant force of 0N
, it will either
remain stationary
(provided it is already stationary), or it will
continue to move at the same, constant velocity.
Newton's 2nd Law
states that an objects
acceleration is proportional to the resultant force
acting on it and
inversely proportional to the
objects
mass
.
Newton's 3rd Law
states that when
two objects exert a force on eachother
; the forces are
equal in magnitude
and
type
but
opposite in direction.
The
tendency
of objects
to remain in rest or uniform motion
is known as
inertia
.
L16 - Velocity and Acceleration
Acceleration = (Final Velocity - Initial Velocity / Time)
a = (v - u / t)
Metres/Second^2 = (m/s - m/s / s)
Deceleration
is an an
acceleration in the other direction
(negative acceleration).
Method:
Set up
air track
and
light gates
; the gates should be fairly far apart and should be
connected to a data logger
(the logger should calculate acceleration)
-
Fix a
piece of string
onto a
pulley
, on
one side of the string, a mass carrier
should be present.
The other side of the string should be connected to the trolley
.
-
The
trolley should
be able to
pass through the second gate before the masses hit the floor
.
-
Steady
the
trolley
, add the
maximum weight increment
and
release the trolley
; record the
acceleration
as stated by the
logger
.
-
When removing weight
from the mass carrier, the
removed weights must be placed back on the trolley
to ensure the
total mass of the system remains the same.
100g ~= 1N of Weight
L19 - Stopping Distances
Stopping distance
is a
sum of the thinking distance and the braking distance.
As
speed increases
, both
braking and thinking distance increases.
Factors that can affect stopping distance:
Drinking
and using
drugs
can increase reaction times (thinking)
-
Weariness
(thinking)
-
Mobile phones/
distractions
(thinking)
-
Weather
conditions; icy road (braking)
-
Poorly maintained
vehicles and
brakes
(braking)
L20 - Momentum
Momentum = Mass x Velocity
p = m x v
kgm/s = kg x m/s
The
more momentum
something has, the
more force it requires to stop.
Some vehicles possess such
features
as
crumple zones, seat belts and air bags
. These features
increase the amount of time of a collision
, therefore
decreasing the force
(momentum is constant).
Force = Momentum / Collision Time
F = p / t
Newtons = kgm/s / s
L22 - Terminal Velocity
When a
skydiver initially jumps
from a plane, the
only force
acting on him
is weight
(caused by acceleration due to gravity). He will
accelerate at a constant rate.
-
As the
diver gets faster
, the
air resistance (drag) acting on him will increase
(increase in
acceleration in the negative direction
). This
will continue
to occur
until the drag acting on the diver is equal to his weight.
-
This
resultant force of 0N
means that the
diver will be travelling at a constant velocity
and will have
no acceleration.
-
This
state can only be exited
if the
diver is to physically change something
. Deploying a
parachute
increases the drag force massively
; creating a
resultant force in the up direction.
The
diver decelerates
. This
diver will still be falling, however.
Terminal velocity
occurs when the
resultant force on a body is 0N.
L23 - v^2 = u^2 + 2as
v^2 = u^2 + 2as
Final velocity^2 = Initial velocity^2 + (2 x Acceleration x Displacement)
(Metres/Second)^2 = (Metres/Second)^2 + (2 x Metres/Second^2 x Metres)