Exam 2 - Chapter 3 Kines Flashcards
Forces in nature can do what to motion?
produce, stop or modify motion
When force produces a push on an object
compression
When force produces a pull on an object
tension
When compression and tension are balanced, the object is said to be
in equilibrium
Force can be generated from _______ and _______ sources.
internal and external
The most common internal force is produced by
muscles
External forces include what types?
Fluid forces, contact forces, and gravity
This external force includes air and liquids
fluid resistance/ fluid force
This external force is described as a force acting in the opposite direction to the desired movement and occurring at the area of contact between the two surfaces
friction/ contact force
This external force is measured as the weight of the body though its COG
gravity
COG stands for what?
Center of Gravity
The point around which the body’s mass is evenly distributed
COG
Forms of fluid resistance include
buoyancy, drag and lift
An upward force equal to the weight of the displaced liquid
buoyancy
resistance to forward motion, of water over air
drag
change in fluid pressure as a result of differences in air or liquid flow velocities around an object
lift
Always produces rotary motion; two or more forces of equal magnitude, but opposite direction, applied to the same object but at different points of application, working together to cause movement
Force couple
center or point around which an object rotates
axis
Movement along a path pertaining to or representing a line that may be straight or curved. All parts of the object move in the same direction at the same speed
Linear motion
size, amount. The pound is the basic unit of measurement in U.S. for the _________ of force
magnitude
Spot on the object where the force is put. For muscular force, it is commonly considered to be at the insertion of muscle to bone.
Point of application
Turning or movement about an axis; parts of the object further from the axis move at a greater speed than those close to the axis
rotary motion
The turning or rotary effect of a force
torque
A physical quantity or force possessing both magnitude or size and direction; can be represented by a straight line.
vector
The pushing together of both sides of the joint toward the center of the joint
joint compression
A pulling apart of the two joint surfaces
joint distraction (traction)
What are Newton’s 3 Laws of motion?
Newton’s Law of Inertia, Newton’s Law of Acceleration, and Newton’s Law of Action and Reaction
If an object is at rest, a force must act on the object to initiate movement
Newton’s Law of Inertia
If an object is already in motion, it will remain in motion
Newton’s Law of Inertia
This describes why an object with less mass will move faster than an object with greater mass
Newton’s Law of Acceleration
This implies that there must be two forces present. Each force acts on the other, with the direction of the forces being opposite and the magnitude of the forces being equal
Newton’s Law of Action and Reaction
Jumping on a trampoline is an example of which of Newton’s Laws?
Action and Reaction
A flat surface or plane that is at an angle to the horizontal surface it is placed upon
inclined plane
a rigid bar that rotates about an axis or fulcrum; downward motion at one end causes upward motion at the opposite end
lever
Also called fulcrum or pivot, the point about which the rigid bar turns
axis
The effort or energy used to move or hold the object
force
Also called effort arm or moment arm; distance from the axis to the point of application of the force
force arm
The object one is trying to move, sometimes referred to as weight or load
resistance
Distance from the axis to the point of application of the resistance or load
resistance arm
F_____R_____A is an example of what class of lever?
Second class lever
A_____F_____R is an example of what class of lever?
Third class lever
What lever is used more for strength?
2nd class levers
What lever is used more for balance and equilibrium?
First class levers
What lever is used more for speed and range?
Third class levers
