# What is its velocity equal to zero?

1. Jun 11, 2012

### saalrom

The function of a bus as a function of time is presented below. At what time is the bus traveling with the greatest velocity? What is its velocity equal to zero? Is there a time where the velocity is negative?
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

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2. Jun 11, 2012

### Villyer

Re: Velocity.

What do you know about the relationship between x(t) and v(t)?

3. Jun 11, 2012

### saalrom

Re: Velocity.

I know that V = (Xf-X1)/T, and that x represents the location of an object and t represents time. V represents velocity.

4. Jun 11, 2012

### Spaghetti

Re: Velocity.

The graph in your problem is showing the position of the bus as time passes.

Think about how the position is changing as time moves on, or possibly over specific intervals of time.

Imagine the position line was going across the graph completely horizontally. That would mean the position isn't changing, so the bus must have no velocity.

Now think about if the position changed greatly over a very small period of time. Since the position is changing very quickly, the bus must be moving very quickly.

And remember that velocity is just speed with a direction. If an object is moving forward at 60 miles per hour, that object has a speed of 60 miles per hour, and a positive velocity of 60 miles per hour. If that same object is then going in the opposite direction (backwards) at 60 miles per hour, that object has a speed of 60 miles per hour, and a negative velocity of 60 miles per hour.

Is there a specific part of the problem you're having trouble with? With just the problem and no thoughts with it, it's a bit difficult to figure out where you're at!

5. Jun 11, 2012

### Villyer

Re: Velocity.

Has any graphical analysis of the graph of x(t) been mentioned before?

For example, what does the slope of a position v. time graph tell you?

6. Jun 11, 2012

### azizlwl

Re: Velocity.

Take a point on the graph.
Take second point which is right to the 1st. point as close as possible.

If point #2>(higher)point #1 then velocity positive
If point #2=point #1 then velocity zero
If point #2<(lower)point #1 then velocity negative