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View Full Version : Accelerating Bodies velocity


hawksavu
Sep 22, 2009, 10:13 AM
Is it possible to have 0velocity in an accelerating body?
If yes please explain:confused:!

ebaines
Sep 22, 2009, 10:26 AM
Sure it's possible. Here's an example: suppose you throw a ball straight up into the air with initial positive (upward) velocity. As the ball rises it goes slower and slower as its velocity decreases due to the force of gravity. At some point its velocity is zero, when it reaches its highest point. Then the ball starts to fall back to earth, and its velocity grows larger and larger, but in a negative (downward) direction. During this entire time the ball has been accelerating downward due to gravity at a rate we call g, about -9.8 m/s^2. So at its apex the object had zero velocity and acceleration of -9.8 m/s^2.

Think of it this way: acceleration is the change in velocity per unit time, so if you plot an object's velocity versus time on a graph then its acceleration is the slope of that line. If the line happens to go through V=0, with either a positive or negative slope, you have zero velocity and non-zero acceleration.