unit 3 test Flashcards
a push or pull
force
this type of force can change the movement of an object
applied force
the sum of all the forces acting on an object
net force
true or false: forces have direction
true
what SI unit is force measured in
newtons (N)
the rules of adding forces
- add forces in the same direction
- subtract forces in opposite directions
- forces not in the same direction or in opposite directions can’t be directly added together
a force applied in one direction is greater than the force applied in the opposite direction (doesn’t change in motion)
balanced force
the force that opposes the sliding motion of 2 surfaces that are touching each other
friction
source of friction
microwelds
what must be applied ts break microwelds.
force
prevents 2 surfaces from sliding past each other
*static friction
opposes the motion of 2 sunfaces sliding past each other
*sliding friction
what causes sliding friction
microworlds constantly breaking and forming as the objects slide past each other
as wheels roll, static friction acts over the area where the wheel & surface are in contact
rolling friction
-an attractive force between any 2 objects that depends on the masses of the objects and the distance between them
gravity
“relationship between the gravitational force between 2. objects, the object’s masses, and the distance between them
the law of universal gravitation:
gravitational force _____ as the mass of either object ______ and the objects move closer
increases; increases
true or false: gravity is a low range force
true
region of space that has a physical quantity at every point
field
true or false all object sunnounded by grenitational field
true
how to measure strength of gravitational field (g)
newtons per kilogram (N/kg)
gravitational force exerted on an object
*weight-
*weight equation:
N = Kg× N/ Kg
fg=mg
true or false weight increases as mass increenses
true
cell phone
IN
backpack w books
100 N
jumbo jet
3.4 m N
true or false
the weight of an object cam change depending on the gravitational fore on the object
states that-an object moves at a constant velocity unless an unbalanced
force acts on it
newton’s first law of motion:
nwetons first law basically says that
- moving object will move a constant velocity unless unbalanced force acts on it
tendency of an object to nesist any change in its motion
inertia-
true/false amount of object’s inertia is related to mass
true
rue / false greater mass, greater chertia.
true
the forces exerted an an dbject, its mass, and its acceleration ale related
newton’s second Law of motion
velocity divided by time it takes for change to occur
*acceleration
the acceleration of an object depends on
its mass t the force exerted on it
*force has ____ and ____
size & direction
when one object exerts a force on a second object, the second object exerts a force on the first that is equal in strength and opposite in direction
newtons 3 law of motion:
forces are interactions…
between objects
2 objects r different masses, still feel the…
same size force
friction-like force that opposes the motion of objects that move through the ain
air resistance
maximum speed an object will reach when falling through a substance, such as air
terminal velocity
when gravity is the only force acting on an object
free fall
force exerted toward the center of a curved path
centripetal force
if no external forces act on a group of objects, their total momentum does not change
*law of conservation of momentum-
objects appear to be ___ in free fall
weightless
air resitance moves directly ____ to motion of object in the air
opposite
air resistance ____ ans objects speed ____
increases; increases
net force ____ as object falls
decreases
terminal velocity depends on _____, _____, and ____
size; shape; mass
to describe velocity, you need to know
speed and direction
is the distance & direction of an object’s change in position from the starting point
displacement
when you graph the motion of an object, you put ____ on the horizontal axis and ____ on the vertical axis.
time; distance
is a condinate system in which the positions of objects can be measured
reference point
Vf
final velocity
occurs with change of speed or direction or both
acceleration
the distances direction of anobject’s change in position from the starting point
displacement-
can either be a change in how fast smth is moving or a change in direction
change in velocity
______ has the same direction as velocity
momentum
when the _____ of an object changes, the object is accelerating
velocity
is the total distance troveled divided by the total time traveled
average speed
the product of an object’s mass & velocity
momentum
speed of object & direction of motion
velocity
rate of change of the velocity of an object
acceleration
the r.o. c. in position @ given point in time
*instantaneous speed
distance an object travels dovided by the time of travel
speed
the r.o, c. of an objectls position
speed
any change over time
rate
