Ch. 2 Sec. 1 Displacement and Velocity Motion in One Dimension

One dimensional motion is the simplest motion Recall: Which area of Physics deals with motion? One dimensional motion: when something can only move two directions, like forward and backwards. Example: A train on the tracks

Frame of reference Sometimes, it’s difficult to describe motion, since a train, for example, could be on the tracks, the tracks are also on the Earth, which is spinning on its axis, which is traveling around the sun!!!!! Frame of reference= a system for specifying the precise location of objects in space and time.

Frame of reference and the train… When you select a frame of reference, its stays fixed for the problem in question and has an origin from which the motion is measured. For the train,, any of the station along its route could serve a s a convenient frame of reference.

Displacement The change in position of an object Formula: Change in position= Final position- initial position P. 41: Figure 2: Gecko 85cm-24cm= 61cm displacement.

Displacement continued ***Displacement does not always equal distance traveled*** Gecko runs up the tree, then back down. Suppose it runs from 20 cm to 80 cm up the tree, then back down to the 50 cm mark. 50-20= 30cm TOTAL displacement Even though, the gecko traveled 90 cm.

Displacement can be positive or negative Table 1 Page 42

Velocity Where an object starts and stops doesn’t completely describe motion Calculating speed and direction is important to fully quantify motion. Average Velocity= the total displacement/ the time interval during which displacement occurred Or, change in position/ change in time

Practice problems P. 44 1-5