Motion Diagrams
Motion diagrams are a pictorial description
of an object in motion. They show an object's position and velocity
at the start, end, and several spots in the middle, along with acceleration
(if any). Click on the links to the right of the diagram to see different motions and the associated diagram.
Steps for making a motion diagram:
-
Draw a box or a dot representing the object
at the start and end of the time of interest.
-
Draw a box or a dot representing the object
at two or three equally spaced intermediate times. If the object
is traveling at a constant rate, these will be equally spaced. If
it is speeding up, they will get progressively further apart. If
it is slowing down, they will get progressively closer together.
-
Draw a vector (arrow) over each box representing
the velocity at that point. The vector will point in the direction
of motion and its length will represent the relative speed of the object
at that point. Label these vectors "V."
-
If the object is speeding up or slowing down,
draw another vector above them representing the acceleration. The
acceleration will be proportional to the difference between a velocity
vector and the one previous to it in time; it will point in the same direction
as the V vectors if the object is speeding up and the opposite direction
if it is slowing down.
-
If the object turns around and comes back,
you may want to make two motion diagrams for clarity; one from the start
until the point that the object turns around, and the other from the point
it turns around to the end.
Exercise created by Scott
Bonham, Western Kentucky University.
Physlet
by Wolfgang Christian, Davidson
College