Mechanics Flashcards
how is constant acceleration represented on a velocity time graph?
straight line
what is the area under the graph of a VT graph?
total displacement
what does a steeper force extension graph mean?
more force required to produce extension
what does a shallower force extension graph mean?
greater extension
what is the elastic limit?
point where elastic becomes inelastic
what is hookes law?
F = k x
force = spring constan in N/m * extension in metres
what is limit of proportionality?
point on force extension graph where line is no longer straight
and no longer obeys hookes law
elastic limit
how is energy stored when the spring is stretched?
as elastic potential energy in the spring (area under the graph)
E = 0.5 fx = 0.5kx^2
what is newtons first law?
an object will remain stationary or at uniform motion
unless resultant force is acted upon it
at rest resultant force = 0
what is newtons second law?
F =M * A
m = kg
a = ms-2
what is netwon third law of motion?
if body exerts force on A
a exerts equal and opposite force on body
how to work out weight?
w= m*g
explain terminal velocity?
falling from rest - as it accelerates the air resistance also accelerates
object gets faster therefore acceleration decreases
object then is moving fast enough for the air resistance to equal the weight and object doesn’t get faster
speed which air resistance = weight is terminal velocity
how is momentum measured?
what is its units?
momentum = mass * velocity
kgm/sec
how to work out force from change in momentum?
force = change in momentum over time
what is work done?
force * distance
whenever force is applied work is done
efficiency formula?
useful output / total energy input
