FINAL (power points)

something that possesses the capability to cause a change in the motion of a system, pull or push

force

forces posses the _ to change motion

capability

forces _ motion, it does not cause motion

changes

what is the unit of force

newtons

1 newton =

1 kg m/s^2

_ are used to graphically represent propertiess of a force

vectors

vectors are used to describe

direction, orientation, point of application, magnitude, line of action

classifications of force

internal, external: contact and noncontact

forces that occur when objects are not touching eachother

external noncontact forces

examples of external noncontact forces

gravity, electromagnetic, nuclear

force that exists between bodies of masss, acts between personal mass and earth's mass, relatively weak

gravity

gravity is a vector quantity, meaning it has _ and _

magnitude and direction

the magnitude of gravity is _ the direction is _

positive, negative

the point at which all of a persons/ objects mass is concentrated

center of mass

where is the gravitational pull on the human body concentrated

center of mass

quanitity of matter of which of a body is composed, measured in kg

mass

force of gravity acting on an object, measured in Newtons

weight

how are mass and weight related

weight = mass times acceleration due to gravity

is it easier to pick up a 20kg box on the earth or the moon

moon

Is it easier to push a 20kg box on the earth or the moon?

same

forces that occur when objects are touching eachother

external contact force

examples of external contact forces

applied, frictional, spring

the initially applied force

applied force

the simultaneous equal counterforce acting in the opposite direction to the action force

reaction force

most common applied force

ground reaction force (GRF)

ground reaction force

force exerted by the ground on the body, equal but opposite direction from body's weight

standing still: GRF=

person's body weight

when moving: GRF increases due to

acceleration

the more dynamic or the more acceleration the task is, the greater amount of GRF is

produced

resists the sliding of two objects that are in contact

frictional force

what do frictional forces help us do

help us maintain balance and prevents slipping during walking

value that represents the difficulty of sliding any given surface over another because of their texture

coefficient of friction

how our organs, bones, muscles, tendons, ligaments, cartilage, and other tissues exert forces on one another

internal forces

muscles contract and produce force via

the sliding filament theory

muscles attach to bone via

tendons

muscles always _ on a bone when contracted

pull

distal end of a segment weighs _ than the proximal end

less

which type of muscle contraction produces the largest muscle force

eccentric

myosin head broken from attachment site on actin

eccentric contraction

which type of muscle contraction can form more cross bridges

eccentric

muscles only produce

internal forces

muscles only can produce to change the motion of

a body's limbs

muscles cannot change the motion of

our body as a whole

in order for a whole body to change motion, what type of force must be applied

external

allows us to account for all forces acting on a body to calculate the overall

net force

study of motion in space with no regard to the forces that cause motion

kinematics

what are the two componets of motion

space and time

kinematics can be defined as a description of

what we see

the action or process of change in position

motion

types of motion

linear (rectilinear, curvilinear), angular, general

what two questions need to be asked to analyze any movement

what is moving, what is it moving in relation to

movement in one direction,

x direction=horizontal

movement in two directions

x direction=horizontal

y direction=vertical

movement in three directions

x direction = left to right

y direction = front to back

z direction = up and down

movement must always be described in _ to something

relation

perspective from which movement is described

reference frame

cartesian coordinate system defined for our purposes is: up and right =

positive

cartesian coordinate system defined for our purposes is: down and left =

negative

quantities that are fully described by a magnitude only

scalar

quantities that are fully described by both magnitude and direction

vector

body's physical location in the reference frame

position

measure of the length of the path followed by the object from initial to final position, does not consider direction, scalar

distance

straight line distance in a specific direction from initial to final position that considers direction of movement and is a vector quantity

displacement

rate of distance, how fast something is moving, scalar

speed

rate of displacement, how fast is something moving in a specific direction, vector

velocity

speed

distance/time

velocity

displacement/time

describes the rate of change in velocity with respect to time, how quickly velocity changes (increasing or decreasing)

acceleration

on average, how long does it take an athlete to reach peak velocity

50-60m

how fast you can change your rate of velocity is often the difference between

sucess and failure

instantaneous acceleration

value at a certain time

occurs when the net external force acting on an object is constant and unchanging

uniform acceleration

what are the two forces acting upon an object in the vertical direction

air resistance and gravity

acceleration due to gravity is

constant

in what direction does gravity only operate in

vertical

what force is ignored in the horizontal direction

air resistance

in the horizontal direction, if velocity is constant, acceleration =

0

motion of bodies projected into the air

projectile motion

what are the only forces that act upon a projectile

air resistance and gravity

what 3 factors influence trajectory of a projectile

projectile angle, projectile velocity, projectile release height

angle at release determines shape of trajectory, optimal angle is based on purpose of activity

projectile angle

velocity at release heigh determines height and range

projectile velocity

difference in height bt vertical takeoff position and vertical landing position

projectile release height

composed of pure horizontal and pure vertical components

resultant vector

when drawing out resultant vectors, what shape is made and what components are each side

right triangle, horizontal velocity (<->) veritical velcoity (up-down), resultant vector (hypotenuse)

where should you begin the y component of a triangle vector diagram

tip of x axis

three components of projectile velocity

resultant velocity, vertical velocity, and horizontal velocity

vertical and horizontal velocity components are __ of each other

independant

resultant vector is the _ of all given individual velocities

sum

who created the laws of motion

Sir Isaac Newton

first law of motion

law of inertia

resistance of an object to changing motion

inertia

Newton's First Law says

an object at rest stays at rest and an object in motion stays in motion at constant speed and direction unless acted upon by an external force

quantifies current state of motion and resistance to change, "mass in motinon" Mass x velocity

linear momentum

what does momentum depend on

mass and velocity

rules of conservation of momentum

if no external forces = constant momentum

total momentum before collision = total momentum after collision

momentum cannot be created or destroyed

two objects bounce off one another after colliding

elastic collision

two objects stay connected to one another after colliding

inelastic collision

quantifies how elastic an objects collision is

coefficient of restitution

second law of motion

law of acceleration