l How do you think scientists can visualize acceleration? A motion graph l What are the two kinds of graphs we have discussed? Position vs. Time Speed vs. Time Jennifer Brown GRAPHING MOTION
position vs. time l The position vs. time graph is a curve when there is acceleration. l The car covers more distance each second, so the position vs. time graph gets steeper each second. Jennifer Brown Sections
l When a car is slowing down, the speed decreases so the car covers less distance each second. l The position vs. time graph gets shallower with time. Jennifer Brown Sections
Jennifer Brown Sections
free fall l An object is in free fall if it is accelerating due to the force of gravity and no other forces are acting on it. l rubiks-cube-skydiving rubiks-cube-skydiving Jennifer Brown Sections
SECTION 4.2 – GRAPHING MOTION : l Constant speed – the speed stays the same l An object moving at constant speed always creates a position vs. time graph that is a straight line. Sections October 19-20, 2011
l Graphs of Motion: The data shows the runner took 10 seconds to run each 50-meter segment. Because the time was the same for each segment, you know the speed was the same for each segment. Sections October 19-20, 2011
l You can use position versus time graphs to compare the motion of different objects. l The steeper the line on a position vs. time graph means a faster speed. l Is this a direct or indirect relationship? Direct relationship Sections October 19-20, 2011
l The steepness of a line is measured by finding its slope. l The slope of a line is the ratio of the “rise” (y axis) to the “run” (x axis). Sections October 19-20, 2011
l Calculating Distance (Speed Vs. Time Graphs): Suppose we draw a rectangle on the speed vs. time graph between the x-axis and the line showing the speed. The area of the rectangle is equal to its length times its height. Sections October 19-20, 2011
l Graphical Relationships: Sections October 19-20, 2011 No relationship between variables
Sections October 19-20, 2011 Weak relationship between variables
Sections October 19-20, 2011 Direct Relationship between variables
l Acceleration is easy to spot on a speed vs. time graph. l Acceleration causes the line to slope up on a speed vs. time graph. What is the bike’s acceleration? Jennifer Brown Sections
l If the hill is steeper, what do you think happens to the acceleration? The acceleration is greater. Jennifer Brown Sections