Term

Definition
quantity of motion, keep on going p=mv units= kg*m/s 


Term
Describe Newton's 2nd law in terms of momentum: 

Definition
rate of change of momentum with respect to time produced by the force 


Term
What is the equation of Newton's 2nd law in terms of momentum? 

Definition
(sum of)F= (mvfmvi) / (change in)t 


Term

Definition
It is the measure required to change the momentum of an object. Unit (N*s) 


Term
how can we manipulate the impulsemomentum relationship i.e. in terms of injury prevention? 

Definition
impulse is the shaded area under a forcetime curve. we can manipulate this relationship by changing the time and/or force, aka a large force over a short time or small force over a large time 


Term
what are examples of spreading an impact out over time? 

Definition
catching an egg, landing from a vertical jump, crumple zone, function of a bike helmet 


Term
draw what the forces loook like for walking and running. what are characteristics of these two graphs? what about the AP force? 

Definition
running: has two peaks (impact peak and active peak). the propulsion phase is less than the breaking phase walking: bimodal phases (2 max)
the AP GRF component has a similiar shape in walking and running; ()AP is a result of a backward horizontal friction, (+)AP phease is near midstance where force is generated by musc pushing against the ground 


Term
where is the center of pressure? 

Definition
indicates the resultant GRF vector, describes location of centroid of pressure distribution 


Term
when is a force a centric force? 

Definition
when a force is applied to an object so that its line of action passes through the object's center of gravity, or a fixed axis of rotation **AS LONG AS IT IS FREE TO MOVE!!! 


Term
what is an example of a centric force? 

Definition
pushing a desk straight, linear motion 


Term
when is a force an eccentric force? 

Definition
if the line of action of force is "off center", change in angular AND linear motion at times 


Term
give an example of an eccentric force: 

Definition
pushing a wheel of a bicycle, it will spin, if the bike is upside down and locked into the floor 


Term
How do these forces relate to our skeletal system? 

Definition
All muscle forces are eccentric; no muscle passes thru the axis of the joint, therefore it produces angular motion of our joints 


Term

Definition
torque, or a moment of force, is the product of the applied force causing a rotation, and the perpendicular distance to its line of action. "It is the turning or rotational effect of an eccentric force"!!!
it is the tendency of a force to cause a rotation about a specific axis 


Term

Definition
NO! it is the effect of a force in causing a rotation 


Term
what are the units for torque? 

Definition


Term
what are two other names for (d)perpendicular? 

Definition
either the torque arm or the moment arm 


Term
M = F * d(perp) is the same equation as T (torque) = F * r (perp distance) 

Definition


Term

Definition
also d(perp), the moment arm is the perp distance from the line of action of the force to the axis of rotation 


Term
if you were given 3 of the same forces at different angles, which force would be most effective? 

Definition
the one with the longest d perpendicular because that means the greatest torque 


Term
How do you calculate the turning effect due to a force? 

Definition


Term
what are the conditions for static equilibrium? what must you do first when calculating static equilibrium? and then what? 

Definition
(sum)F=0, (sum)Maxis=0, so Mcw=Mccw calculate ALL moments first find sum of moments after so essentially (sum)CCW(+)=(sum)CW() 


Term
is muscle moment arm greater or smaller than d(perp) of external force? 

Definition
much smaller! think of your flexors insertion, and then think of the dumbbell far away 


Term
How much more is muscle force than weight of dumbbell? Why are we built the way we are, why not longer d(perp)? 

Definition
about 8 times larger or more and we would have to reposition the orgin or insertion (aka wings) small amount of shortening for large angular displacement 


Term
dynamic situations: does the moment due to the weight of the dumbbell stay the same during a bicep curl? what is the position when d is minimized or maximized? 

Definition
NO! no because the moment arm is changing d(minimized) is either straight or all the way flexed d(max) is 90 degrees 


Term
dynamic situations: does the moment due to the force produced by the muscle stay the same during the bicep curl? 

Definition
no... changes as moment due to weight of dumbbell changes, also muscle moment arm changes 


Term
Looking at a GRF walking, running, graph, talk about BW, magnitude, time 

Definition
BW in walking is 1x as great BW, running is 25x as great magnitude: vary as a function of locomotor speed, so increase when running 

