Forces and Thier Measurements Flashcards
Force
effect that one body has on another
Internal force
within the system
external force
outside of the system
is force a scalar or vector?
vector (magnitude and direction)
point of application of force
necessry for determining moments and torques
Pressure
Force/area
force is distributed “force per cross sectional area”
Newtons 1st law
Intertia
Newtons 2nd law
F=ma
newtons 3rd law
action reaction
free body diagram
all external forces acting on the body
GRF
Ground Reaction Force
with no movement = to mass
GRF-W = ma
Positive Acceleration
increasing V - upward direction
decreasing velocity - downward direction
change direction from down to up
negative acceleration
decreasing V in upward Direction
increasing v in down direction
changing direction from up to down
zero acceleration
constant v
peak v
What does this graph and A and B represent?
Walking GRF - double bump
A weight acceptance
B. push off
Running GRF
In a biphasic wave what indicates velocity?
Slope of the line
What does friction do?
opposes the tendency to move
Ffriction=coefficient of friction * Normal reaction force.
In which direction does normal force exert its influence?
perpendicular to surface
As friction increases
force increases and vice versa
Cause of angular motion
eccentric force
centric force
-linear motion only
-line of action passes through objects COM
force couple
-angular motion only
-force with a resultant moment but no resultant force
eccentric force
general motion (linear/angular)
Torque
Moment of force: turning effect, cause of angular motion
moment arm
perpendicular distance from the axis of rotation to the line of action.
changes as angle changes
Newtons laws of angular motion
law of angular inertia t=rotating body continues to rotate
law of angular acceleration T=la torque equals product of moment of inertia and angular acceleration
law of angular reaction T12=f12*d for every torque equal but opposite torque
A in Static equilibrium
No acceleration,
dynamic equilibrium
Inertial forces
Impulse
Cause of change in momentum
Impulse momentum relationship
accounts for force and duration of force applied
how does segmental momentum relate to total body momentum?
segments are summed to find total body momentum
sum of all momentums
total momentum of a system
if force is zero what is acceleration?
zero
what is momentum without impulse?
unchanged
giving impulse examples
batting
throwing
