# Shared Flashcard Set

Biomechanics
Exam 1
33
Physiology
09/29/2011

## Additional Physiology Flashcards

Term
 What is the most important noncontact force?
Definition
 gravity
Term
 What is Newton's Law of Gravitation state and what is the formula?
Definition
 It describes the concept of gravity. Any two particles attract one another with a force directly proportional to the product of their masses and inversely proportinal to the square of their distances between center of massF = (G x m1 x m2) / r^2
Term
 What is weight? And what is the equation? And units?
Definition
 It is a vector quantity and it is the attractive force of the earth on an objectW = mg (newtons), where g = 9.81m/s^2
Term
 What are the units of mass?
Definition
 it is a scalar quantity and it is kg
Term
 What is the effect produced by gravity?
Definition
 Acceleration
Term
 Is the acceleration due to gravity the same everywhere on the earth's surface?
Definition
 No, because the points on the earth are not equidistant from its center! Not perfect spherical
Term
 Through what point does the resultant force act on a body?
Definition
 Through the center of gravity (CG).Does not always have to be within the physical limits of the body
Term
 What are the forces that influence a projectile's flight?
Definition
 Gravity (vertical only) and Air resistance (always opposes motion, we will use negligible air resistance)
Term
 What are the (3) factors we control to manipulate flight trajectory?
Definition
 Speed of release, and height of release, and angle of release,
Term
 What is the point in time at which an object is considered a projectile? And what is the flight path of a projectile called?
Definition
 The instant of release. It's called a trajectory. This type of motion has no external forces acting on it except for gravity and air
Term
 Without air resistnace, a projectile's flight path is called what? And what is the highest point called?
Definition
 A parabola, and the apex
Term
 what happens to d(horizontal) in each of these cases:speed increase.. dh ..?heigh increase.. dh ..?
Definition
 speed increase.. dh ..increasesheight increase.. dh ..increases, because vh is the same BUT t(tot) increases because the object has farther to fall
Term
 How do we know if motion is angular?
Definition
 If 2 pts on the same body move different distances in a given time
Term
 if h=0, what is the optimal angle of release for a projectile?
Definition
 45 degrees. 30 degrees and 60 degrees will have a shorter horizontal distance
Term
 If speed is held constant, what happens to the optimal angle as you increase the height?
Definition
 the optimal angle decreases AWAY from 45 degrees
Term
 If height is held constant, increasing the speed of release results in what for the optimum angle?
Definition
 getting closer to 45 degrees
Term
 to which factor is d(horizontal) most sensitive to?
Definition
 SPEED or v
Term
 What is a very important feature of human motion?
Definition
 Segment rotations combine to produce linear motion of the whole body
Term
 Key concept: motion of any point on a rotating body can be described in linear terms. What info is required?
Definition
 1. axis of rotation2. location of point of interest relative to axis
Term
 What are the units for angular velocity? What are the units if you are using angular velocity in an equation?
Definition
 degrees/s but if you are using it in an equation it must be in radians/second!
Term
 what is the formula for linear and angular displacement? and what units?
Definition
 d=(theta)(r)where d is the linear dist the point of interest has traveledtheta is the angular distand r is the linear distance that the point of interest is located from the axistheta MUST be expressed in radians!!!!!!!!!
Term
 what is the formula for linear and angular velocity?
Definition
 V(tangential)=w x rw - angular velocity in rad/s!!!r - radius of rotation of point of interest
Term
 how do you convert from degrees to radians?
Definition
 divide the degrees by 57.3 to get radiansmultiply the radians by 57.3 to get degrees
Term
 what are you doing if you are maximizing v(tangential)? aand how do you do it?
Definition
 you are maximizing the linear velocity of a point located distally on a rotating bodymaximize vt by...increase wincrease rincrease both
Term
 why is it difficult for an athlete to maintain w if r is increased, vice versa?
Definition
 moment of inertiathink of a sledge hammer
Term
 What happens during linear and angular acceleration, what is the object forced to do?
Definition
 Follow a curved path due to inertia. The continuous change in direction represents change in direction of velocity i.e. acceleration!
Term
 what is centripetal acceleration?
Definition
 the linear acceleration that describes the change in the DIRECTION of v(tangential) of an object foloowing a curved path (aka radial acceleration)
Term
 what is tangential acceleration?
Definition
 a(t) - the linear acceleratoin that describes the rate of change in MAGNITUDE of tangential velocity
Term
 give an example of centripetal acceleration and its effects
Definition
 as a hammer thrower spins just before release, the hammer follows a curved path. at release, there is no more centripetal force and the hammer takes off along a tangent line
Term
 explain the physics of a sprinter running a curve
Definition
 they are continual undergoing a change in direction, i.e. there is an a(centripetal).
Term
 for all rotational and curvilinear motions, resultant acceleration =
Definition
 the vector sum of the centripetal and tangential accelerations
Term
 what is the formula for centripetal acceleration? and what happens if you change some of the variables?
Definition
 a(c)=[v(t)^2]*r = (w^2)*rif you increase v(t), higher force is needed to maintain curved path (produce ac)if you decrease r (radius), results in higher ac, also need greater force to maintain curved path
Term
 what is the advantage of banked turns?
Definition
 banking faciltates development of centripetal force, so less dependent on friction as a source of centripetal force
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