an object's change in position relative to a reference point
frame of reference
stationary background needed to detect motion
a quantity with direction
the change in position of an object
how fast an object moves
common units of speed
an object moves equal distances in equal times
speed at a certain time (speedometer)
How does average speed differ from instantaneous speed?
average is speed calculated over a time interval; instantaneous is the speed at a certain time (speedometer)
speed in a direction
the rate of change in velocity
What causes acceleration?
Change in speed or change in direction.
the acceleration of an object moving in a circle
What mathematical equations define acceleration?
1. a = vf - fi / t
2. vf= vi + at
What units are used with acceleration?
m / sec / sec or m / sec2
a push or a pull
unit of force
What are the 4 fundamental forces?
3. strong nuclear
4. weak nuclear
Which fundamental force is the strongest?
Which fundamental force is the weakest?
forces that don't cancel out
How do unbalanced forces affect motion?
they cause acceleration
sets that cancel out
force between objects that opposes motion
4 types of friction
friction between objects at rest
friction between moving objects
What types of friction are classified as kinetic?
How is unwanted friction reduced?
When is friction helpful?
when objects need to be accelerated
quantity with magnitude only; no direction