 # Hands-On-PhysicsMECHANICS

## - Analysis -

### Speed

Testing the Aircart's speed involves two variables, the distance traveled and the time required to travel that distance. If you set the distance (say, to one meter), then distance (d) is the independent variable, and you must measure time (t) which would be the dependent variable in this case. If, on the other hand, you choose the pick a time (say, three seconds) then time is the independent variable and you must measure distance, the dependent variable. In this case distance depends on the time you choose.

After making several "runs" to get a few measurements, calculate the average time or distance.

( Average Measurement = sum of measurements / number of measurements).

Calculating the average speed is easy, it's just the ratio of distance to time, d / t. However, the final speed, that is, the speed at the end of the interval, is bigger than the average speed because the Aircart is speeding up. If the Aircart starts it's run from rest (zero speed), then the final speed is twice the average.

Double the time or distance and measure you aircart's average speed again.

How "fast" is your aircart?

You could setup a straight test track three meters long to evaluate your AirCart. Mark the start, 0.5 meter, 1.5 meters, and 3 meters. Use the lap timer to measure the time to travel each of the three sections. ### Suggestions for Analyzing Your Aircart

1. Calculate its average speed over the half-meter (starting from rest).
2. Calculate its average speed over middle one-meter (after it has sped up for half a meter).
3. Calculate its average speed over last 1.5 meters.
4. Calculate the acceleration over the first half meter of the track.
(Over the first meter these aircarts have a nearly constant acceleration.)
5. The aircart's initial speed was zero, and you can calculate other three speeds, That means you can also calculate three accelerations.

Click here for more information about calculating speeds.

### Questions

Does your AirCart have a constant acceleration over the entire trip?
Does your AirCart have a constant speed after three meters?

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