Transcript Speed - PBworks

SPEED
how fast an object moves
S=distance/time
Measured in m/s
Average speed=total distance and total
time
(can speed up or slow down)
Constant speed=same distance in equal
amounts of time
(does not speed up or slow down)
VELOCITY
Quantity describing both speed
and direction
Circular motion: direction is
always changing so velocity is
changing
Measured in m/s with a
direction
velocity= distance / time
MOMENTUM
Depends on both its velocity and
itm mass and has direction
Equation: momentum= mass x
velocity
.
Measured in kg m/s with direction
Greater mass or faster velocity=
more momentum
ACCELERATION
Any change in velocity
Equation is
acceleration= final velocity – initial velocity
time
+acceleration = speeding up
- Acceleration = slowing down
FRICTION
A force that acts against the direction
of motion
A rough surface increases friction
A smooth surface decreases friction
Static friction is a reaction force and
does not exist is there is no other
force trying to change the motion of
the object
AIR RESISTANCE
Caused by the interaction between
the surface of a moving object
and air molecules
Larger surface areas will have
greater air resistance so
streamline the object so that air
passes around the object more
smoothly (aerodynamic)
GRAVITY
Force of attraction between any two
objects
Mass and distance affect
gravitational force
INERTIA
The resistance of an object to any
change in its motion.
The tendency of an object at rest to
remain at rest.
More mass= greater the inertia
Harder to start, stop or change
direction
WEIGHT
Measures the pull of gravity on an
object’s mass
force(wt)= mass x acceleration(9.8)
if you weigh 76 kg x 9.8 m/s2=745
N
Your force/wt would be 745 N
If you went to the moon, your
force/wt would be 1/6 that amount.
76 kgs x 1.6=122 N.
FREE FALL
The motion of a body when
only the force of gravity is
acting on it
Results from gravity
2
for earth 9.8 m/s
For moon 1.6 m/s2
TERMINAL VELOCITY
When two forces are equal, the object stops
accelerating and reaches its maximum
velocity
Jump= when air resistance and force of
gravity are equal= terminal velocity of 320
km/h
Open chute= air resistance increases
slowing them down
New terminal velocity of 6 km/h so they can
safely land.
LAW OF CONSERVATION OF
MOMENTUM
The total amount of momentum
in a system in conserved.
The total momentum of two
cars before a collision is the
same as the total momentum
after the collision.
FORCE
A push or a pull, always comes in pairs working in
opposite directions
Net force: combination of all of the forces acting on an
object
Determines if the velocity of the object will change
Balanced forces: forces acting on an object that combine
to produce a net force of zero 0
Unbalanced forces: forces acting on an object that
combine to produce a net force other than zero 0
Examples: gravity, friction, weight