Thames & Kosmos DLX, Руководство по эксперименту, Страница: 97 / 132

Pedal to the metal with
the sports car
YOU WILL NEED
› The assembled sports car
› IR remote control
› 5 AA batteries or 5 AA rechargeable batteries
› Masking tape
› Measuring tape
› Stop watch, note pad, and pen
HERE’S HOW
1. For this experiment, you will need a large room,
because your “race track” should be as long and
straight as possible. A hallway or corridor is perfect.
2. Use masking tape to mark a starting line at one end of
the track and a finish line at the other. Make sure to
leave a safety zone beyond the finish line so your car
doesn’t crash into the wall.
3. Precisely measure the distance from the starting line to
the finish line, down to the millimeter. The track should
be as long as possible so as to reduce the effects of
inaccuracy in your time measurements.
4. Drive your sports car right up to the starting line. Ask
someone to operate the stop watch. Ready, set, go!
5. As soon as your sports car has completely crossed the
finish line, note the time. Write it down in your note pad
and repeat the procedure 10 times for each driver.
6. Repeat the series of experiments on different surfaces.
This will help you figure out whether a surface with
more “grip” or traction allows you to make faster
times.
WHAT’S HAPPENING
In this experiment, you repeated the same
experiment several times under the same
conditions. Scientists often perform a series of
tests or experiments in exactly this same way.
This is because in a single experiment, it’s easy to
do something wrong — press the stopwatch too
soon or too late, for example.
This kind of error can be prevented by
performing a series of experiments. In our
case, performing it ten times gave us ten
sets of results. You add these together and
divide by the number of experiments (that
is, 10). The final result is the average of all
of them.
A longer track has the advantage of reducing the impact of any measurement error. For
example, if you were too react just a tenth of a second too late with the stop watch at the start of the
race, it would inevitably result in a measurement error by that amount. If your car needs, say, three
seconds to run the entire track, the impact of this error (0.1 seconds out of 3 seconds = 3.33%) is much
less than with a track that your car runs in just 0.5 seconds (0.1 seconds out of 0.5 seconds = 20%). See
Experiment 12 to find out how to convert speed to the familiar km/h unit.
WANT MORE?
EXPERIMENT 15
95
Driving Robots