SI unit for speed/velocity
m/s (meters per second)
SI unit for acceleration
m/s² (meters per second squared)
Graph: distance vs. time (slope)
slope = velocity
Graph: speed vs. time (slope)
slope = acceleration
the combination of all forces acting on an object
When is friction greatest?
When surfaces or rough, but overall shapes are flat.
Speed is increasing
Speed is decreasing
Acceleration is zero
The object is not moving
Position is increasing (object moving forward)
Position is decreasing (object moving backward)
Velocity is zero
Object is not moving.
Speed and direction
When changing direction
This is a change in velocity, so acceleration applies!
friction between objects that are stationary
friction between moving surfaces
the friction force that acts on rolling objects
the force that opposes motion between two surfaces that are touching
example of kinetic friction
the friction between your car windshield and the air as you drive down the road
the fundamental forces
gravity, electromagnetic force, weak nuclear force, strong nuclear force (aka gravity, charges, nuclear)
On a speed vs. time graph, constant acceleration is represented by...
A straight line
On a distance vs. time graph, constant velocity is represented by
A straight line
Distance vs. time graph with a constant velocity of 10cm/s
Please allow access to your computer’s microphone to use Voice Recording.
We can’t access your microphone!
Click the icon above to update your browser permissions above and try again
Reload the page to try again!
Press Cmd-0 to reset your zoom
Press Ctrl-0 to reset your zoom
It looks like your browser might be zoomed in or out. Your browser needs to be zoomed to a normal size to record audio.
Your microphone is muted
For help fixing this issue, see this FAQ.