Position ~ Time Graph vs Displacement ~ Time Graph

In summary, the conversation discusses the differences between displacement and distance, and how position is a vector quantity that may or may not have a direction. It emphasizes the importance of considering the context and defining directions clearly to avoid confusion.
  • #1
BizzPhizz
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1. Are these two the same? I'm not sure. Sometimes my teacher labels the Y axis with a Delta Displacement [E]. Other times it's just Position (M), so I'm not sure how to identify if we are finding Speed or Velocity.

I'm just assuming they are the same.

2. Also, position is a Vector quantity, but if it's not given a direction, can we assume it's the same as distance?

Thanks,
BizzPhizz
 
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  • #2
Welcome to PF;
1. They are not the same, and the one you want should be clear from the context.

displacements have a direction ... if you all the way around a circle with radius R, back to where you started, then you have traveled a distance ##d=2\pi R## but your displacement is ##\vec{d}=0##.

2. No. again, the directions should be clear from the context ... if not, define some that make sense to you. Often motion is in 1D or along a track so you can only go forward or backward, then one direction is just shown as positive and the other one as negative.

Care must be taken over the signs of acceleration vectors in that case since a negative acceleration could mean you are slowing down in a + direction or speeding up in the - direction.
 

1. What is the difference between a position-time graph and a displacement-time graph?

A position-time graph shows the change in an object's position over time, while a displacement-time graph shows the change in an object's displacement (distance from its starting point) over time. In other words, a position-time graph measures an object's location, while a displacement-time graph measures its change in location.

2. How do you interpret a position-time graph?

The slope of a position-time graph represents an object's velocity, or its speed and direction of motion. A steeper slope indicates a greater velocity, while a flatter slope indicates a slower velocity. The position of the object at any given point on the graph can also be determined by looking at the y-axis.

3. How do you interpret a displacement-time graph?

The slope of a displacement-time graph represents an object's velocity, similar to a position-time graph. However, the y-intercept of a displacement-time graph represents the object's initial displacement, or its position at the beginning of the time interval being measured. The area under the curve of a displacement-time graph represents the total distance traveled by the object.

4. What is the relationship between a position-time graph and a displacement-time graph?

A position-time graph and a displacement-time graph are closely related, as they both show an object's motion over time. However, the position-time graph shows the object's exact location at each point in time, while the displacement-time graph only shows the change in distance from the object's starting point. The two graphs can be converted into each other by taking the derivative or integral, respectively.

5. How do you use a position-time graph and a displacement-time graph to analyze an object's motion?

To analyze an object's motion, you can use the position-time and displacement-time graphs to determine its velocity, acceleration, and distance traveled. By looking at the slope and shape of the graphs, you can also identify changes in the object's speed and direction of motion. Additionally, the area under the curve of a velocity-time graph can be used to calculate an object's displacement and the area under the curve of an acceleration-time graph can be used to calculate an object's change in velocity.

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