WEEK 7 Flashcards
define the law of inertia and describe it (x2)
the tendency of an object to keep its current state of motion
- inertia represents the difficulty in changing that state of motion of an object (resistance to change)
- this is directly proportional to an objects mass
define linear momentum and describe it
quantity of motion possessed by an object
- this is a product of a bodies mass and its velocity
- equation= momentum is equal to mass x velocity. (kg.m/s)
describe overall momentum
a change in a bodies momentum may be caused by either a change in boys mass or change in velocity or both
define conservation of momentum
and describe it (x2)
in the abscence of external forces, the total momentum of a given system remains constant.
- momentum before impact= momentum after impact
- mass before and velocity before= mass after and velocity after.
define impulse and describe ( x3)
def= the force exerted on an object for a period of time
- net force exerted on an object
- effect of force is explained in terms of its impulse
impulse= force x time (newton seconds)
describe impulse peak force relationship
- area calculated for each time interval
- the total impulse= the sum of all areas
- net impulse= determines the net change in momentum
describe braking impulse (x3)
- decrease horizontal velocity of object
- decrease horizontal momentum of body
- if braking impulse= propulsive impulse then there is NO change in velocity, No change in momentum of body during step.
describe propulsive impulse (x2)
- increase velocity of object
- increase momentum of body
list the 3 equations relating to impulse to momentum relationship.
1) force= mass x velocity2- velocity 1 divided by time
2) force x time= (velocity2- velocity1)
3) impulse= mass x velocity2- mass x velocity1.
strategies in sports: describe how sports maximise peak force
- batting or golf swing
- increasing impulse therefore release velocity is increasing by range of motion:
by increasing time that force is applied, the greater impulse and in turn increasing release velocity.
strategies in sport: describe sports that minimise peak force
- marking the ball
- having thicker sole of shoes
- front of sole reduces time compressing foam ( force transmitted into ground )
define the coefficient of restitution
the collision of two bodies over an extremely small time interval during which the bodies exert relatively large forces.
- the number that serves as an index of elasticity for colliding bodies
define perfectly elastic impact and give an eg
the impact during which the velocity of the system is conserved
eg superball
define perfectly plastic impact and give an eg
impact resulting in the total loss of system velocity
eg dropping an egg
