the distance travelled by an object in one unit if time
distance divided by time
the units of speed are m/s or m/s _1
velocity
units of velocity are m/s or m/s-1
distance divide by time
speed in a given direction
acceleration
the change in speed divided by the time taken for the change
final speed-first speed dividedby th time taken
for the change in speed
units of acceleration are m/s2 or ms-2
force
causes a stationary object to move
unit is newton=N
types of resources:magnetic force,electric
force,force of gravity,force of friction
Friction
a force tha opposes the sliding motion
of an object when in contact with
another
advantages:slows you are going to fast in a car.slows you
down when you are going to fast on a bicycle.needed when walking.
disadvantages:can give you blisters when walking in
new shoesmore fuel is needed in a car bacause
when air hits a car it is friction.wears away parts of
cars or bicycle
reduce friction by lubricants such as oil
graph in hard back on difference
between weight and mass
hookies law:the extensin of an
elastic body(a spring)is directly
proportional to the force causing
the extension
moment,levers and centre of gravity
calculating the moment of a force=forcw multiplied by perpendicular
distance from fulcrum to the line of action of the force
levers
a ridgid body that can turn about a fixed point called fulcrum
study page 292
eg:scissors,wheelbarrow and door
law of the lever is when a lever is
balanced the sum of the clockwise
moments equals the anticlockwise
moments
centre of gravity
the centre of gravity of an object is a point in the object
through all the weight of an object appears to act.
equilibrium
when an object is balanced and
still,the object is called equilibrium
the three stages of equilibrium
stable equilibrium:the ball will return to
the same position if given a slight push
unstableequilibrium:the ball will not ruturn to
the same position if given a slight push
neutral equilibrium:the ball will to a similar position is
given a slight push