Motion in One
Dimension
Frame of reference, distance and
displacement
One-dimensional motion is the
simplest form motion
One way to simplify the concept of motion is to
consider only the kinds of motion that take place
in one direction.
An example would be the motion of a commuter
train on a straight track. On a straight track, the
train can only move forward or backward.
(Physics Serway/Faughn pg 36 - Holt)
Frame of Reference
Physicists usually choose a frame of reference
against which changes in position can be
measured.
The frame of reference
selected remains fixed
for the problem in question
and has an origin or
starting point from which
motion is measured.
If an object is at rest (not moving), its position
does not change with respect to a fixed frame
of reference.
For example, the benches on the platform of
one subway station never move down the
tracks to another station. (pg37)
Distance and Displacement
• Distance – the length of actual travel or
how much an object has moved.
• Displacement – the length of a straight
line drawn from the object’s initial (starting)
position to the object’s final position.
Distance is the total length of the object’s
movement, while displacement is the
shortest distance between initial position
and final position).
(pg37)
• Gecko displacement and distance (pg37)
about 62cm
• Gecko displacement and distance (pg37)
Positive and negative displacement
In the Physics text, unless otherwise
stated, towards the right or east will be
considered the positive direction, and left
or west will be negative.
(pg 38) #1
• #1 answer
#2
#2 answer
#3
#3 answer
#4
#4 answer
#5
#5 answer
Physics Classroom web site
http://www.physicsclassroom.com/Class/1DKin/U1L1c.cfm
Total displacement is the distance from
position A to position D