lecture 10 Flashcards
(19 cards)
what is inertia?
resistance of a body that changes in its linear motion
what is moment of inertia?
resistance of a body that changes in its angular motion
what does resistance to a rotation depend on?
mass and how the mass is distributed with respect to the axis of rotation
what is the equation for moment of inertia?
I = m r^2
moment of inertia = mass (kg) times distance from axis of rotation squared
how does weight impact rotation?
the more massive a body is, the more difficult it is to start and stop rotating it.
(high moment of inertia, high resistance to change in movement)
what are the teaching implications to this for children (inertia)?
appropriate equipment for children will enable them to develop correct movement patterns
use smaller - easier to rotate
would it be beneficial to increase knee flexion of the recovering leg when sprinting ? why ?
increased flexion of recovering leg is more effective as it reduces I of the leg around the transverse axis of rotation, thus the swing through is faster
what is the equation for momentum
momentum = mass x velocity
the faster the body moves and the leader a moving body us, the more momentum it has
what is the equation for angular momentum?
angular momentum = movement of inertia x angular velocity
what is angular momentum??
the amount of (potential for) rotation
what is newtons 1st law of angular motion?
if no external torque are applied then the boys angular momentum remains unchanged
gravity does no cause any rotation during projectile motion, as it acts through the CoG.
newtons 2nd law of angular motion?
if the arte of change in angular momentum (anguale acceleration) of a body is porportional to the torque acting on it and is in the direction that the torque acts
newtons 3rd law of angular motion?
for every torque that is entered by one body on another there is an equal and opposite torque extorted by the second body on the first
what happens when we combine law 1 and 3?
angular motion of body parts can change, by transferring angular momentum from one body part to another
what can you increase that will increases angular momentum?
force applied, moment arm and time over which torque acts
in term of moment of inertia, the more massive a body us………..
the more difficult it is to start rotating it or stop rotating it
the more the mass concentrated further away from the axis of rotation
the more difficult it is to accelerate angularly
what is the equation for moment of inertia?
I = m r^2
moment of inertia is equal to mass in kg multiplied by the distance from axis of rotation(radius) squared
what are the unit for moment of inertia
kg.m^2
