Linear Kinetics 1 Flashcards
What is kinetics
The concept of mass, force, and energy as they affect motion
What is Newtons 1st law
Law of Inertia - an object at rest tends to stay at rest, and an object in uniform motion tends to stay in uniform motion unless acted upon by a net external force.
What is Inertia
Resistance to a change in state of motion
What quantifies inertia
Mass
when is an object at rest
When the net forces acting on it sum to zero
What is static equilibrium
when the sum of the forces acting on the person in all axis directions are zero and the person will maintain their state of rest or zero velocity
What is dynamic equilibrium
When an object is in uniform motion. Net forces are equal to zero but an object is in motion
Uniform motion means…
constant velocity (so an object will maintain its velocity unless accelerated or decelerated
Constant velocity means
no acceleration
What is momentum
The tendency for an object to resist change in motion and continue to move in its direction of travel
Is momentum the same as inertia?
no but they are related
What is inertia?
an objects tendency to resist change in the state of motion (at motion and rest), however during motion an object is said to have momentum)
What is the equation for momentum
P = mv
mass x velocity
Is momentum scalar or vector
vector
Understanding momentum is really important when…
dealing with things that collide
What is the law of conservation of momentum
in the absense of external forces, the total momentum of a given system is conserved (is constant)
The sum of the momentum before the collision but equal…
the sum of momentum after the collision
What are two types of collisions
elastic and inelastic
What are inelastic collisions
objects stick together and usually become distorted and generate heat
What is the coefficient of restitution
a means of quantifying how elastic the collisions are. Defined as the absolute value of the ratio of the velocity of separation to the velocity of approach
What is the velocity of approach
the difference between the velocities of the two colliding object just before the collision
What is the velocity of separation
the dfference between the velocities of the two colliding objects just after the collision
For perfectly elastic collisions the coefficient of restitution is __
1
For perfectly inelastic collisions the coefficient of restitution is __
0
what occurs to the momentum of objects in a perfectly elastic collision
each object transfers all of its momentum to the other object
What is the transfer of momentum from sit to stand
By leaning forward our trunk has momentum which can be used to assist in hip and leg extension
During a complex task such as high jump we use transfer of momentum to
help us increase our vertical velocity. The free limbs contribute by transferring their individual momentum to the velocity of the whole body
In high jump, the combined free limb RM reaches a peak when?
Just after the lead leg but just before the arms.
the relative momentum of all tfree limbs _____ at take-off
reduces
What is the law of acceleration
A force applied to a body causes an acceleration of that body of a magnitude proportional to the force, in the direction of the force, and inversely proportional to the body’s mass. F = ma
What is the law of Reaction
Every applied force is accompanied by a reaction force, equal in magnitude and opposite in direction
