Some Graphs for Non-Accelerated Motion
As we have already discussed, Newton's First Law of Motion applies only to objects on which zero net force is acting. In other words, Newton's First Law of Motion discusses objects which are in mechanical equilibrium, and an object in mechanical equilibrium must be doing one of two things:
In addition, we know what some of the graphs for an object in mechanical equilibrium look like. The Net Force Versus Time graph for an object in mechanical equilibrium is ALWAYS a horizontal line which is located on the horizontal axis. The Velocity Versus Time graph for an object in mechanical equilibrium is ALWAYS a horizontal line, too, but its location depends on whether the object is moving and, if the object is moving, on the sign of the velocity of the object. You can see the Net Force Versus Time graph for an object in mechanical equilibrium below and to the left, and you can see the three possible Velocity Versus Time graphs for an object in mechanical equilibrium below and to the right. Remember: Newton's First Law of Motion applies ONLY to objects which are in mechanical equilibrium.
- an object in mechanical equilibrium must be at rest or
- must be moving at a constant speed in a straight line (at a constant velocity).
In addition, we know what some of the graphs for an object in mechanical equilibrium look like. The Net Force Versus Time graph for an object in mechanical equilibrium is ALWAYS a horizontal line which is located on the horizontal axis. The Velocity Versus Time graph for an object in mechanical equilibrium is ALWAYS a horizontal line, too, but its location depends on whether the object is moving and, if the object is moving, on the sign of the velocity of the object. You can see the Net Force Versus Time graph for an object in mechanical equilibrium below and to the left, and you can see the three possible Velocity Versus Time graphs for an object in mechanical equilibrium below and to the right. Remember: Newton's First Law of Motion applies ONLY to objects which are in mechanical equilibrium.
See the Net Force Versus Time graph below. Click to enlarge. |
See the Velocity Versus Time graphs below. Click to enlarge.
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