# Distance-time Graph and Velocity-time Graphs

1. Feb 17, 2006

### Alain12345

Can someone please explain to me how to draw a velocity-time graph from a distance-time graph? Are there any general rules about drawing a VT graph from DT graph?

Thanks a lot.

2. Feb 17, 2006

### assyrian_77

From a DT graph, you can obtain the velocity at different times. With that information you can draw your VT graph.

3. Feb 17, 2006

### Staff: Mentor

Are you familiar with the mathematical relationships between position, velocity and acceleration?

4. Feb 17, 2006

### Alain12345

Yes I am, but I'm having trouble drawing th graphs.

5. Feb 17, 2006

### Staff: Mentor

Well then, if the velocity is constant, what does the position do with respect to time?

6. Feb 17, 2006

### robphy

Velocity is the slope on the distance vs. time graph.

Beneath your distance vs time graph, setup the axes for the velocity vs time.... choose the same scale on the time axis for both position and velocity... and line them up.

Now, for each time t, visit the point [event] on the position graph and imagine zooming in. Assuming a smooth enough motion, the graph near that point looks like a line [in your viewport]. Determine the slope of that line and plot, for that time t, the value on the velocity graph. [If you are just doing a sketch, just approximate that slope... is the slope positive, negative, or zero? After advancing to a later time, does that slope increase, decrease or stay the same? It may help to "ride the position graph" with your left hand.]

Try that out.