Question

A train leaves the station heading south on the tracks. It takes the train 5 seconds to reach 50 miles per hour. It completes the entire 100 mile trip in two hours. Calculate the train's average speed and velocity over the two hour trip. Show your work. Identify if each of the measurments are a scalar or vector quantity.

Answer 1

The only piece of information we need is "It completes the entire 100 mile trip in two hours," and that it is heading south.
The acceleration is just to make people confuzzled.
Average speed is defined to be the magnitude of displacement over time.
Average Speed = 100miles/2hours
Average Speed = 50miles/hour , or simply 50miles/hour
This reason that speed is in magnitude is that speed is a scalar quantity; there is no direction assosiated with it.

For the average velocity, the calculation is the same.
Average Velocity = 100miles[SOUTH]/2hours
Average Velocity = 50miles/hour[SOUTH]
The magnitude of both speed and velocity are the same, however, velocity has a direction (it is a vector). As indicated, the train travels south, so you must somehow denote this.

You can denote the direction in many ways, ask your teacher for his/her preference.
Here are some examples:
50miles/hour[South]
50miles/hour[S]
50miles/hour or 270 degrees -----------> where 0 degrees is East, 90 is North, 180 is West, and 270 is South.

Answer 2

wow your smart (: