Week 9 Flashcards
how would you describe momentum in terms of sport
a team can have good or bad momentum which means they are continuously playing good or bad and predicted to continue to do so
newtons first law
an object or body will continue in its state of motion unless acted on by an external force
what is the equation for momentum
P = m* v
units of momentum
kg*m/s
what is momentum the product of
mass of an object and the velocity at which it is moving
how do you change momentum
either change its mass or apply an external force that will changes its velocity
what is newtons second law
a mass will accelerate in proportion to the net force acting on it
equation that goes with newtons second law
F = m*a
how do you change momentum in terms of impulse
impulse is the force applied over a given time that causes the velocity of a mass to change
F* delta t = m* delta v
can mass ever change to help momentum
when thinking of a space ship yes but the human body can be assumed a constant mass so impulse will cause a change in velocity only
what is newtons third law
every reaction has an equal or opposite reaction (F1 = -F2) as long as no additional external forces are present
what does the impulse-momentum relation ship allow us to do
evaluate the effectiveness of a force in producing motion or stopping motion
how do you calculate impulse
impulse = F * delta t
a. if force is 200 N and time is 2 seconds what will the impulse be
b. if this impulse is applied to a 75kg mass, what will the change in velocity be
400 N*s
5.3 m/s = delta v
when thinking of impulse realistically it is unlikely that the force profile is constant so how do we measure impulse?
take the area under the curve using a time window to calculate impulse and add them together
total/sum of all Fdt = mv final - mv initial
what do force plates tell us
reaction forces (usually ground)
F = m*a
where F = sum of all forces acting on the plate
so it cannot tell us a specific segment that is moving on the plate
a = acceleration of COM (doesn’t know how it moved)
if F = m*a what does F vertical =
F vertical + mg = ma
F vertical + m(-9.81) = m (-value)
F vertical = m(9.81-value)
what assumptions do we make when talking about projectile motion
a body when in contact with no other object is only under the effect of the force of gravity
a final = ?
v final = ?
d final =
a initial
v initial + adt
d initial + v finaldt+0.5adt^2
equation for angular momentum
L=I*w
where w = angular velocity
L = angular momentum
I = moment of inertia
angular impulse-momentum theorem
Mdelta t = Iw final - Iw initial
derived from M=Iangular acceleration
what is the equation for the moment of inertia
I=m*k^2
where k = radius of gyration (distance at when a point mass would have the same I as the distributed mass
definition of moment of inertia
an objects tendency to resist a change in its angular velocity
