Chapter 11 Flashcards
Force
push or pull applied by one object and experienced by another
Net force
= all forces acting on object
What adds together for net force?
forces in the same direction
What subtracts from the net force
forces in the acting in the opposite direction
Weight
force of planet on an object near that planet
force of friction
force of a surface on an object
friction force acts _ to surface
parallel
kinetic friction
force of friction when something is moving along the surface
kinetic force acts
opposite the direction of motion
static friction
friction force between two surfaces that aren’t moving relative to one another
normal force
force of a surface on an object
normal force acts _ to the surface
perpendicular
coefficient of friciton
number that tells how sticky two surfaces are
Newton’s 3rd law
force of Object A on Object B is equal in amount and opposite in direction to the force of Object B on Object A
Newton’s 2nd law
object’s acceleration = (net force it experiences/mass) and is in the direction of net force
how is a force often measured in a laboratory
spring scale
Two aspects of force
- what objects were involved, how much force, which direction of force
- calculate net force acting on object to object’s change in velocity
an object can _ a force, not _ a force
experience/have
canonical
conforming to general rule
free body diagram has
- labeled arrow representing each force, with each arrow beginning on the object and pointing in the direction in which the force acts
- List of all the forces acting on the object, indicating the object applying the force and the object experiencing the force
Which forces can act on an object without contact?
gravitational and electrical
instead of the term gravity, use _
weight: force of Earth on car
all free-body diagram starts with
gravity
weight acts
downward
any other forces must be a result of
contact
all forces must be exerted by an
identifiable object
how to determine net force with acceleration in a direction
net force = mass * acceleration
when an object moves along a surface, the acceleration in a direction perpendicular to that surface must be
net force perpendicular to the surface is 0
kinetic friction force =
coefficient of kinetic friction times the normal force
coefficient of friction
property of the surfaces in contact (less sticky, coefficient of friction decreases = less friction = smaller force of friction)
coefficient of friction takes 2 forms
static and kinetic
coefficient of static friction is used for something that is
stationary
coefficient of kinetic friction if the object is
moving
coefficient of static friction is a _ value
maximum
maximum coefficient of static friction =
- find how much horizontal pushing force will just barely make the book move
- use formula
how to find 3rd law companion force
- look at description of force in free-body diagram and reverse objects applying and experiencing the force
If net force has both vertical and horizontal component, use _ to determine the magnitude of the net force
pythagorean theorm
If net force has both vertical and horizontal component, use
tangent to determine the direction of net force
Newton’s third law companion forces/ Newton’s third law force pair
force of object A on object B is equal in amount and opposite in direction to the force of object B on Object A. Those two forces are the pair
when a force acts at an angle measured from the horizontal, the vertical component of that force is =
amount of the force itself * sine of angle
when force acts at an angle measured from the horizontal, the horizontal component of that force =
amount of force itself * cosine of angle
