Kinesiology- Forces
true/false- the more work in time = less power?
false- more power
Negative ground reaction forces will do what?
increase impact to the body on landing
3 types of friction
static, sliding and rolling.
if there is too much stress, what happens?
there is permanent distortion
define- negative work
work done in the opposite direction the body is moving (eccentric exercises)
true/ false- force of 1 body is matched by and equal force in the same direction
false- force of 1 body is matched by an equal force in the opposite direction
true/ false- sliding friction has only a small area in contact with the ground
false- rolling friction
true/false- the lower the coefficient of elasticity, the lower the angle of rebound due to less distortion
false- the greater the angle of rebound
Law of reaction states
for every action, there is an equal and opposite reaction
Define- work
force applied against resistance over a particular distance
coefficient of elasticity is?
force divided by distortion
Define: summation of forces
force generated by muscles are added from 1 segment to another and causes it to move faster.
3 examples of composite forces
force of kick, force of gravity and force of wind
Define: concurrent forces
forces acting at the same point of application bue at different angles.
define- strain energy
form of stored energy, if object has the ability to rebound after distortion. (pole vault)
define- static friction
friction between 2 resting objects opposing initiation of motion
What happens to friction at low speeds as speed increases?
friction decreases
Magnitude must be what to move an object?
greater than the object's inertia
the relation of kinetic energy and momentum (3)
how much depends on mass and velocity, for every increase in velocity, the increase the work, if doubled mass = doubling the amount of kinetic energy
sprinters, speed skaters, and rowers use what to build momentum and acceleration?
impulse and cadence
Muscular force is?
in direct proportion to the number and size of muscle fibers. muscles usually act in a group and the point of application is where the muscles insert.
momentum can be changed by?
increase or decrease of object's mass, velocity or both.
with increased mass comes?
increased inertia
equation of inertia
inertia = mass + resistance to change in movement. mass = gravity (9.81).
3 forms of energy
kinetic, potential and strain
the names of newtons 3 laws are?
law of inertia, law of acceleration and law of reaction
3 types of composite forces
linear, concurrent, and parallel
Impulse of law of acceleration
longer time we apply force, the more the objects aceleration will increase. it is used to slow down to prevent injury
3 qualities of forces
magnitude, direction, and point of application
define- kinetic energy
mass on the move
Define- point of application
point at which force is being applied
Define- momentum
product of mass x velocity
Positive ground reaction forces will do what?
propel forward, into the air, etc.
define- sliding friction
resistive force between 2 objects that are sliding/ rubbing eachother
define- rolling friction
resistive force between a round object that is rolling over a surface
define potential energy
stored energy. ready to put to work due to its position.
5 types of elasticity
tension, compression, bending, tortion, and shearing
Law of inertia states?
that the body continues in a state of rest of motion unless acted upon by another unbalanced force
define- elasticity
the ability to resist distortion and return to regular size adn shape.
Action line is also known as?
the line of pull
with spinning balls on vert. surfaces, the ball will have?
the same speed with horizontal. speed
the amount of recoil depends on?
the type of surface it comes in contact with
Factors of force will determine what?
the type of which motion will occur.
the more stress applied causes what to happen with distortion?
to increase
the 4 effects of spin on the ball?
top spin, back spin, no spin, spinning balls with vertical surfaces.
examples of concurrent forces
triceps, gastroc and soleus, deltoid, steering wheel
t/f- anything above or off the ground is potential energy?
true
t/f- the more mass and faster moving the increased kinetic energy and momentum
true
true/ false- due to the factors, there are rules that limit each rolling friction factor?
true
true/ false- force applied in direction of motion will increase momentum and vise versa?
true
true/ false- static friction is the worst kind of friction
true
true/ false- the more friction between objects, the lower the angle of rebound
true
true/false- with no sping, hte ball will develop top spin if there is any angle of contact?
true
Tortion is a?
twisting force ( twist apple)
Rolling friction depends on what 3 things?
type of surfaces in contact, amount of pressure pushing them together, and the diameter of rolling object
What is a force that modify motion?
weight (force of gravity on mass)
magnitudes formula
weight = mass x gravitational pull
Linear force is..?
when it is applied in the same direction along the same action line, or vise versa.
tension is?
when stretch is applied and it returns to normal
define-positive work
work done in the same direction the body is moving (biceps curl)
true/ false you must overcome sliding friction to gain motion?
false, static friction
Define- composite forces
2 or more forces acting on an object.
Friction is between?
2 solid surfaces
Define- parallel forces
Forces that do not have the same action line, but act parallel to eachother.
true/ false- muscles work separately from one another
false, muscles work in groups, they are known as the composite muscles of the body
If you are on different parts of the earth what will happen and why?
You can be heavier or lighter. heavier if you are closer to the center of the earth due to increased pull
shearing is?
a rubbing force (abrasion when falling to ground)
Law of acceleration states?
acceleration of an object is directly proportional to the force causing it, in the same direction of that force, and it's inversly proportional to its mass.
any change in momentum is what to the impulse that produced it?
equal
Newton's law of Gravitations states..?
all ovjects are attracted to eachother in direct proportion to mass and inversly proportional to the distance between them (the larger and close together the objects are the more attracted they are)
Define- power
amount of work done in a particular time
Angle of rebound depends on what? (5)
angle of velocity of contact, if ball was spinning at the angle of contact, coefficient of elasticity, how much friction is present and the temperature of the object (if temp is increased, rebound increases)
Define- conservation of momentum
any forces that act on eachother, the momentum is constant.
with top spin, a rebound is?
at a lower angle with higher horizontal speed
with back spin, the rebound is?
at higher angle with decreased horizontal speed
bending is?
bending an object (paper clip)
Components of parallel forces (5)
can act in the same and different directions, if forces are balances it means no motion, if forces are unbalance it means rotation motion, if 2 parallel forces opposite to eachother is means rotation and if 2 parallel forces are equal and same direction it means they r linear
define- energy
capacity of a person or object to do work
No motion does what to work?
causes no work
at high speeds, there is a proportional increase in friction causing what?
causing the generation of heat and disinigrating the object
Define- anatomic pulley
change the angle of pull of a muscle so we increase the rotary component and improve mechanical advantage
what is due to teh direction, and point at which force is being applied?
composite forces
compression is?
compressing an object, like a stress ball.
examples of things that limit rolling friction factors
dimples on a golf ball (aids in flight), bike tires (narrow for speed or wide for friction)
the closer the force is applied in direction of desired motion, the more fluid motion will be is considered what?
direction of force
coefficient of elasticity equation is
e= square root of bounce height divided by drop height. the closer to 1 is the more elastic
Things rebound in a predictable manner depending on what 5 things?
elasticity, mass, velocity of rebounding surface, friction between surfaces, and angle of contact
define- conservation
energy changing between forms