Mechanics Flashcards
given constant acceleration, we have 5 quantities of motion - suvat, which stands for
s = displacement
u = initial velocity
v - final velocity
a = acceleration
t = time
modelling assumption
particle :
- mass of object concentrated at a single point
- rotational forces/air resistance can be ignored
smooth/light pulley
- no friction, means tension is the same on either side of the pulley
- pulley has no mass
rod:
- mass is concentrated along the line
peg/support
- dimensionless and fixed. can be rough or smooth
uniform body - mass is concentrated at a single point
rough surface - object in contact with the surface experience a frictional force
smooth surface - no friction
inextensible string - acceleration is the same
earth gravity number
9.8
units
mass - kg
length/displacement - m
speed / velocity - m s ^-1
acceleration - ms^-2
force/weight - N (kg m s^-2)
how to convert to vector form from scalar form
use basic trig to find the x and y
how to convert from vector to scalar
find the magnitude
velocity and speed
velocity is vector
speed is scalar
average velocity equation
displacement from starting point/time taken
average speed equation
total distance travelled/time taken
acceleration is
the rate of change of velocity
the area under a velocity time graph is…
the distance travelled
differentiating displacement gives…
velocity, and integrating velocity gives displacement
deceleration =
gradient
deceleration =
gradient
deceleration =
gradient
weight equation
W = mg (mass x gravity)
what is the normal reaction
a force that acts perpendicular to the surface
newtons 1st law of motion
states that an object at rest will stay at rest
- an object moving with constant velocity will remain at that velocity
- unless an unbalanced force acts on that object
newtons second law
F=ma
if a particle is at equilibrium…
- it’s at rest or moving at constant velocity
- there is no resultant force
- left = up and right=down
