unit 2 test 1
what is a scalar
a quantity requiring a number only to describe them
what is a vector
a quantity requiring a number (magnitude) and a direction
how are vectors written diff to scalars
bolded/underlines
is distance a scalar or vector
scalar bc just number
position is what
place relative to referance point (zero)
in metres
vector
what is displacement
change in position
has magnitude and direction
thus vector
final pos minus og pos
what is speed
rate of change of distance
how far travelled per unit of time
scalar
how to find speed
distance travelled/time taken
what is velocity
rate of change of displacement
change in position per unit of time
vector
how to find velocity
displacement/time taken
what does instantaneous speed/velocity show
gives indication if how fast smt is moving at a moment in time
what does average speed/velocity show
an indicatiok of how fast smt is moving over an interval of time
during which the instantaneous speed/velocity has likely changed
thus avg
units for speed/velocity
m/s or km/h
to find each from each you divide or multiply by 3.6 (m/s to km/h is x3.6)
what is acceleration
rate of CHANGE of velocity
change per unit of time
how to find acceleration
triangle velocity/ triangle time
thus its a vector
through motion, objects are either
stationary (zero velocity)
moving w/ constant velocity (zero accel)
or accelerating uniformly/constantly
the 5 variables of the equations of motion are
s= displavement between initial/final position (metres)
u= initial velocity (ms^-1)
v= final velocity (ms^-1)
a=acceleration (ms^-2)
t= time between initial/final pos (s) (only scalar one)
equation of motion 1 (def of accel)
a=triangleV/triangle t
also = v-u/t
or v=u+ut
equations of motion 2 (def of avg velocity)
Vavg= s/t
or Vavg= (u+v)/2
so s/t=(u+v)/2
therefore s=((u+v)t)/2
equations of motion 3 (displacement)
area=s=𝒖𝑡+1/2 𝒂𝑡^2
Since 𝒂=∆𝒗/𝑡 so ∆𝒗=𝒂𝑡:
𝒔=𝒖𝑡+1/2×𝑡×𝒂×𝑡
therefore s=ut+1/2a(t)^2
equations of motion 4
𝒖=𝒗−𝒂𝑡
thus 𝒔=𝒗𝑡−1/2 𝒂𝑡^2
motions of equations 5
𝑡=(𝒗−𝒖)/𝒂
therefore 𝒗^2=𝒖^2+2𝒂𝒔
what is gravity's constant acceleration
9.8ms^-2 downwards