Biomechanics exam 3

Mass

Amount of matter

Weight

The effect of gravity on mass

Inertia

Resisting change in motion

Center of gravity

The location of object in which all the mass is evenly distributed

Work

Force x distance

Power

Force x distance/time , force x velocity

Rectilinear motion

Straight line

Curvilinear motion

Curved line

What is linear motion measured by?

Linear displacement (feet, meters, etc)

Energy

Ability to do work

Nuclear, heat, chemical, electrical, mechanical are examples of

Energy

3 forms of mechanical energy

Kinetic, gravitation potential energy, elastic potential energy

Kinetic energy

Energy of motion, KE = ½ x mass x velocity 2

Gravitation potential energy

PE = weight x height above the ground

Elastic potential energy

Ability to do work while recoiling from being stretched/ compressed

Energy can neither be created nor destroyed but it is constantly

Converted

There has be a- to have a change in motion

Net external force

The force you exert against the earth when walking is the

Internal force

The force of the earth pushing against you when walking is the

External force

The forces exchanged when walking is an example of the

Ground reaction force

What is the external force of bringing the fist up toward the shoulder

Force from bicep

4 properties of a force

Magnitude, direction, point of application, line of action

Rotary motion

When an object is restricted to moving around a fixed axes

Radius of rotation

Distance from axis to rotating object

What is rotary motion measured by?

Angular displacement (degrees)

Pressure

Force acting over a given area , force/ area

The environment will deliver a-- in response to the force the body exerts on the environment

Reaction force

Newtons 3rd law of Motion

For every force applied by one body on a second, the second body applies an equal and oppositely directed force on the first

If you're sprinting off a block, you are not moving into the ground meaning you are the - force?

Internal

When knee extension happens, the quads are the - force

External

The internal force and external force are - in magnitude

Equal

The arrow depicting force is called a

Force vector

Friction force

Normal force x coefficient of friction

Normal friction

Force pushing surfaces together

Coefficient of friction

The roughness of the surface

A high coefficient of friction means friction is

High

Centripetal force

Responsible for continually forcing the rotating object to follow circular path (inward)

Centrifugal force

Equal and opposite reaction force of centripetal force

Centripetal formula

Mass x speed 2 / radius of circle

Small radius of a turn needs- centripetal force; large radius needs-

More, less

Coefficient of elasticity (e)

Sq route of height of rebound/ height of drop

Vector quantities

Magnitude and direction - force

Scalar quantities

Magnitude only- mass, volume, area

Net effect is determined by __

Vector composition

Vector composition

More than one external force applied to a system (going from 2 to 1)

The - shows where the ball will go

Resultant vector

Colinear forces

Forces have the same line of action

Vector resolution is _ of the vector composition process

Reverse

Vector resolution

Taking a vector and breaking it into vertical and horizontal components (going from 1 to 2)

When performing a bicep curl, what are the 2 components

Stabilizing and rotary

When an external force acts on a system which is restricted to moving around an axis, the result is

Rotary motion

2 rules for force to cause torque

Eccentric force, force must not pass through axis

Eccentric force

Away from axis (not in the center)

Torque formula

Force x force arm

Force arm

Shortest distance from axis to the line of action of the force, only perpendicular distance

Clockwise -, counter clockwise _

-, +

Force is measured in newtons, force arm is measured in meters. What is torque expressed as?

Newton meters (Nm)

The rotary motion and response of a segment is determined by the-

Net torque

When would you want the torque of a weight to be stronger than the torque of your arm?

Eccentric training

4 functions of a machine

Balance forces, provide advantage in force, provide advantage in ROM and movement speed, and change force direction

3 machine-like structures used by the body

Lever, wheel -axle, and pulley

A: muscle force vector, B: weight of arm force vector, C: weight of briefcase force vector, D: weight of briefcase force arm E: weight of arm force arm, F: muscle force arm

A: bicep force, B: bicep force arm, C: weight force arm , D: weight force

90 degree angle of pull- - force arm

Longest

Muscles of the body are at a biomechanical - when it comes to force

Disadvantage

Muscles of the body are at a biomechanical - when it comes to range of motion and speed of movement

Advantage

How are levers classified?

According to position of axis, motive force, and resistive force

First class lever

Axis is between the motive force and resistive force

What kind of levers are the triceps and calf muscles?

First class

Second class lever

The resistive force is between the motive force and axis

A nutcracker is an example of a - lever

Second class

Third class levers

The motive force is between the resistive force and axis

What kind of lever are most concentric body movements

Third class

What kind of lever is an eccentric body movement

Second class

Where is the motive force applied on the wheel axle machine of an automobile?

The axle

The medial and lateral malleoulus are examples of _

Pulleys