Follow up notes on Motion

The Position of an object gives its location The Position of an object gives its location. In order to describe something’s position you need to establish a frame of reference. So, a position vs. time graph will describe where an object is at various times. So, such a graph can show us if the object is moving, how fast it is moving and which way! Let’s look at a graph:

Review of Motion The y-intercept of the graph tells you where the object started. The slope of the graph tells you the velocity of the object. That’s both how fast the object is traveling and which direction it’s moving.

Recall that the definition of slope is often stated as “Rise over Run”. Slope on a position- time graph is the same thing as Velocity!!

The graph to the right shows data for a rolling ball. a) Where did the ball start?___________  b) How fast is the ball moving? (It’s speed?)  c) How long would it take for the ball to roll a distance of 36 meters?

Helpful Points: If it is a straight line, the object was at constant speed. If the line is steep, the object is fast If the line is more flat, the object is slow If the y-intercept is close to zero, the object started near the frame of reference If the y-intercept is not near zero, the object started far away from the frame of reference

If the line slants or curves up, the object is going away from the F.O.R. If the line slants or curves down, ,the object is going towards the F.O.R. If the curve begins to go vertical, the object is speeding up. If the curve begins to go horizontal, the object is slowing down. If the line is straight and exactly horizontal, the object is not moving.

Description of Motion

I. ) At which point(s) is the speed of the object constant II.) Where is the object NOT moving? _______________ III.) Where is the object traveling in the positive direction? _______________ IV.) Where is the object slowing down? _______________ V.) Where is the object traveling in the negative direction? _______________

VI.) Where is the object speeding up? ______________ VII.) Where is the velocity of the object decreasing? _______________ VIII.) Where is the velocity of the object increasing? _______________ IX.) Where does the object have the faster constant velocity? _______________ X.) Where is the slowest constant velocity? ____________________________ _______________

I.) At which point(s) is the speed of the object constant? B and E II.) Where is the object NOT moving? C III.) Where is the object traveling in the positive direction? All but C IV.) Where is the object slowing down? D V.) Where is the object traveling in the negative direction? None

VI.) Where is the object speeding up? A VII.) Where is the velocity of the object decreasing? D VIII.) Where is the velocity of the object increasing? A IX.) Where does the object have the faster constant velocity? B X.) Where is the slowest constant velocity? E