Chapter 1: Forces Flashcards
Force
A push or pull exerted by one object, on another object
Force pairs are ___in size but act in ___direction on each object
equal, opposite
What causes (or tends to cause) an object to accelerate?
start, stop, speed up, slow down, change direction
Forces are measured in
SI: Netwon (N) English: pound (lb)
The size of push or pull
Magnitude
Line of action
Direction
Which way a force is pushing or pulling
Sense
Where the push or pull is applied on the object
Point of application
What 2 quantities does a vector require?
Magnitude and direction
True or False? The effect of the forces acting on the body are not affected by changes in the dimensions or shape
ie. hitting a water balloon vs baseball with a baseball bat
True
Pair of forces that act WITHIN the object or system
-hold the object together
Internal force
Two types of internal force, one pulls (tension) and one squeezes (compression)
Tensile force and compressive force
Muscles pull on ____, which pull on____.
tendons, bones
Bones push on ____, which pushes on other____ and bone
cartilage
A type of force that acts on an object or system through interaction with environment
External force
A type of external force where objects touch each other
Contact force
A type of external force where objects are not touching each other
Noncontact force
A type of external force that is the weight of an object
Gravitational force
Force of gravity acting on an object
Weight
Formula for Weight
W= m*g
W=weight in newtons
m=mass in kg
g=acceleration due to gravity= 9.81 m/s squared or approx 10m/s squared
What is the numerical value for g (acceleration d/t gravity)
9.81 m/s squared downward, or 10 m/s squared
True or false, contact forces occur not only when object touch each other, but each force acts separately on one of the objects.
-Also called reaction forces
True
A normal contact force is _____ to the two objects in contact
perpendicular
A parallel contact force is____to contacting surfaces of two objects
-also known as ___force
-opposes motion or sliding between surfaces
parallel, friction
Static friction is when two surfaces are not/are moving on each other
NOT
The maximum friction before objects start to slide
Limiting friction
Dynamic friction is when two surfaces are/are not moving on each other
ARE
Two other names for Dynamic friction
sliding or kinetic friction
The great the R (normal reaction force) the greater the ____affected by characteristics of the two materials in contact represented by___.
friction, greek drippy looking u (greek letter mu)
Formula for friction
F=uR
The sum of all external forces acting on one object
-also called resultant force
-not simply summing all external force magnitudes, must account for ___of each external force
Net force, direction
____ forces is one or more external forces with the same line as action, with identifying one direction as ____ and the opposite direction as _____
Colinear, positive and negative
___forces are not colinear but act through the same point. Example of this force: ____
Conccurrent, gymnast hanging from grab bar
Formula for concurrent forces
RF squared = HF (net hoizontal force) squared + VF (net vertical force) squared
True or false: Sometimes external forses are not colinear and do not act only in the horizontal and vertical directions
Tues
