kinematics Flashcards
what are the standard SI units for quantities
Mass= kilogram= KG
Displacement/length=Metres=M
Time=seconds=S
Speed/velocity= Metres per second= m s-1
acceleration=Metres per second per second= M s-2
Forece/weight=newton=N
why do we write s-1 when we mean per second
because per second is the same as 1/second
eg to find the metres per second you would do how many metres divided by the seconds
which is the same as m/s but because s-1 is just 1/s it is the same thing anyway
WHEN ANYTHING IS PER IT IS ALWAYS TO THE POWER OF -1
Convert distance and speed to vector quantities
vector quantities have a direction as well as a magnitude so
speed=velocity
distance=displacement
can distance and displacement be negative
distance cannot be negative as it is only magnitude
because displacement has a direction if it goes in the negative direction (shown in question) it can be negative
how to work out average velocity
displacement from start divided by time
(so if overall displacement is 0 then the average velocity is also zero)
compared to speed which is just distance divided by time.
have to divide vector by another vector
points about a displacement time graph
-the gradient is the velocity ( as change in y/ change in x on a displacement time graph is just displacement/ time which is velocity
-steeper the line means the object is travelling faster
- if the gradient is negative it just means that the object is travelling back towards the start
how to work out acceleration on a velocity time graph
the gradient
how to work out distance travelled on a velocity time graph
the area underneath the graph
key points about a velocity time graph
-the gradient= acceleration
- negative gradient means you are decelerating
- area under velocity time graph is the distance travelled
- if the area is bellow the x axis you are travelling back towards the starting point.
which formulea do we use when there is CONSTANT acceleration
s.u.v.a.t
what does SUVAT stand for
