EXAM 1 Flashcards
Law of Inertia
In the absence of a net force, the state of motion of an object will not change
Law of action reaction
If one body exerts a force on a second body, the second exerts back on the first a force of equal magnitude but opposite in direction
There is always a _____, never just a ____
pair of forces, single force
What are forces?
A push or pull (effect that one body has on another)
Force is a …
vector
- has magnitude + direction
Internal forces
Within an object or system, tensile-internal pulling forces
What if tensile/compressive forces are greater than what the structure can withstand?
The structure fails or breaks
What is the only thing that can produce internal forces within the body?
Muscles
External forces
Act on an object as a result of interaction with the environment
Non-contact force
An external force that can occur even if objects aren’t touching (gravity)
What tools do we use to measure external forces on the body?
Force plates, load cells, and pressure sensors
What tools do we use to measure internal forces on the body?
Buckle transducers and fiber optic cables
Transient impact peak
Force of high magnitude and short period of time
Colinear forces
Forces have the same line of action (may act in the same or different directions)
Concurrent forces
Forces that don’t act along the same line of action but about the same point (must calculate horizontal and vertical forces separately)
Static equilibrium
There are no net external forces acting on an object
Frictional forces
Opposes sliding or motion between objects in contact
What does μ mean in the friction equation?
coefficient of friction
What does R mean in the friction equation?
Normal force
Does surface area have an impact on friction force?
no
postion
location in space
distance
length of total path traveled
- scalar quant
displacement
diff b/w starting and ending point
- vector quant
acceleration
Describes rate of change of velocity with respect to time
stride
Ipsilateral heel strike to ipsilateral heel strike
step
Ipsilateral heel strike to contralateral heel strike
Rectilinear motion
All points on a body move in a straight line so that direction of motion does not change, orientation does not change, and all points on the object move the same distance
Curvilinear motion
All points on a body move so that the orientation of the object does not change and all points move the same distance. Paths are curved so direction of motion is constantly changing even though orientation is not changing
angular motion
All points on a body move in circles, or parts of a circle about the same fixed central line or axis
