Describing motion with graphs Physical science

You can use graphs to determine the velocity of an object

Constant rightward (+) velocity- 10m/s

Car is moving with a changing rightward velocity

Motion with changing positive velocity will result in a line of changing positive slope

Whatever characteristics the velocity has the slope (line) will exhibit the same characteristics If it’s a straight line = constant speed If it’s a curved line = acceleration by speeding up or slowing down If line starts at zero= the object is starting at the F.O.R. If the line does not start at zero= the object is either: -starting near the F.O.R and going away or towards F.O.R. -starting far from the F.O.R. and going away or towards F.O.R.

What can we say about the motion of these two graphs?

The graph below represents a negative velocity

Check your understanding: use the slope to determine the motion of the objects

X t B A C A … Starts at home (origin) and goes forward slowly B … Not moving (position remains constant as time progresses) C … Turns around and goes in the other direction quickly, passing up home

Different Velocity-time graphs

E. Graphing Motion slope = speed steeper slope = straight line = * E. Graphing Motion 07/16/96 Distance-Time Graph A B slope = steeper slope = straight line = flat line = speed faster speed constant speed no motion *

E. Graphing Motion Who started out faster? A (steeper slope) Distance-Time Graph A B Who started out faster? A (steeper slope) Who had a constant speed? A Describe B from 10-20 min. B stopped moving Find their average speeds. A = (2400m)/(30min) A = 80 m/min B = (1200m) /(30min) B = 40 m/min

None of the graphs below. Which of the following distance-time graphs shows a person moving closer to a reference point? Graph 1 Graph 2 Graph 3 None of the graphs below. 1 2 3 d (m) Time (s) Time (s) Time (s)

Which of the following shows a person moving at a constant rate? Graph 1 only. Graph 2 only. Graph 3 only. Graphs 1 & 2. Graphs 1, 2, and 3. 1 2 3 d (m) Time (s) Time (s) Time (s)

Graph 1 Graph 2 Graph 3 None of the above. Which of the following shows a person moving the fastest away from the reference point? Graph 1 Graph 2 Graph 3 None of the above. 2 3 1 d (m) Time (s) Time (s) Time (s)

A straight horizontal line A slanted line moving up and to the right. How would a position-time graph appear for an object at that is not moving? A straight horizontal line A slanted line moving up and to the right. A curved line curving up and to the right. A slanted line moving down and to the left.