Lecture 2 Flashcards
(34 cards)
What are the components of force?
- point of application
- line of application
- direction of push or pull
- magnitude
What is a vector?
magnitude and direction
what is a scalar?
magnitude
what is internal forces
- act within the object or system
- joint reaction force and keep joint together
- muscles as a means for motion
what is an external force
- act on an object as a result of its interaction with the environment
- can change the motion of the body center of mass
- contact vs. non contact
What are non contact forces
these are forces that occur even if objects are not touching each other
–gravity (g)
What is gravity
gravity is a non contact force and the force of gravity acting on the body is weigth
[W=mg or F=ma]
** acceleration due to gravity is =9.81 m/s2
What are contact forces
forces that occur between objects in contact with each other
- they can either be soild or liquid
- and can be resolved into componenet forces
- *parallel (friction)
- *perpendicular (normal)
What is the resultant force
this is the sum of the X and Y forces acting on a object
what is friction ?
a force acting over the area of contact between tow surfaces
- the direction is opposite of motion or motions tendency
- determines the relative ease of difficulty of motion for tow objects in contact
- magnitude is the product of the coeffiecient of friction and the normal reaction forces
what is static friction
friction force between two non moving surfaces
(friction is applied equally in an upward line
what is kinetic friction
friction force between two moving surfaces
the friction is constant in a stright line
what is max static friction
this is the highest point before movement
What are colinear forces
these are forces that act in the same or opposite direction and are very simple to calculate
what are the 4 directions and their value
Left= negative Right= positive Down = negative Up= positive
how do you connect vectors
tip to tail
1 place a V at the origin
2 place the tail of the other V at the tip of the 1st
3 then the resultant V is the straight line from the tail of the 1st V to the Tip of the last V
what is the net force
is the sum of all external forces
what is sin
o/h
what is cos
a/h
what is tan
o/a
when is soh cah toa used
when looking at a 90 degree angle
when do you use law of cosines
when you dont have a 90 degree angle
A2 + B2 -2ABcos=C2
What are torques
the rotary effect of a force about an axis of rotation
T=Fd
-turning effect produced by a force
-angular equivalent of a force
- also called moments of force or moments
where do you find the moment arm
the moment arm is the perpendicular from the force line of action to the axis of rotation
