1.3 Quantities for describing motion
Tuesday, September 27, 2016
11:07 AM
Time and time interval Time (clock reading) t is the reading on a clock or some other timemeasuring
instrument. Time interval (t 2 t 1 ) or t is the difference of two times. In the
at time t 4 = 4.0 s at position x 4 = 40.0 m. Thus, the cyclist is moving in the positive direction relative to
reference frame 2.
Simplify and diagram
Since the size of the cyclist is small compared to the distance he is traveling, we can represent him a
Screen clipping taken: 9/27/2016 11:58 AM
.3 A cyclist In Conceptual Exercise 1.2, you constructed graphs for the motion of a cyclist using two
different reference frames. Now construct mathematical representations (equations) for the cyclists
motion for
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Screen clipping taken: 9/27/2016 11:56 AM
Sketch and translate
According to Table 1.4, the observer in reference frame 1 sees the cyclist (the object of interest) at time
t 0 = 0.0 s at position x 0 = 40.0 m and a
1.1
Motion is a change in an objects position relative to a given observer during a certain change in time.
Without identifying the observer, it is impossible to say whether the object of interest moved. Physicists
say motion is relative, meaning that the

o Position is constant with time
A horizontal line on a velocity vs time graph means the object is moving at constant velocity
o Velocity doesnt change with time
Finding Displacement from a velocity graph


For constant velocity linear motion, the pos
Etkina
The dots in these more
detailed motion diagrams
indicate the objects
position at equal time
intervals; velocity arrows
and velocity change arrows are also included. A u v arrow points in the same direction as the u v arrows
when the object is speed
6.1.
When the external force is in the direction of the objects displacement, the eternal force
does positive work
o Causes system to gain energy
If external force is opposite displacement, external force does negative work
o Causes system to lose energy