Answer:
The impression of the image on the retina lasts for about 1/16th of a second after the removal of the object. If a burning stick of incense is revolved at a rate of more than sixteen revolutions per second, we see a circle of red light due to persistence of vision.
Explanation:
If she has a choice and the wiring details are stated on the packaging,
then Janelle should look for lights that are wired in parallel within the
string, and she should avoid lights that are wired in series within the string.
If a single light in a parallel string fails, then only that one goes out.
The rest of the lights in the string continue to shimmer and glimmer.
If a single light in a series string fails, then ALL of the lights in that string
go out, and it's a substantial engineering challenge to determine which light
actually failed.
|Acceleration| = (change in speed) / (time for the change).
Change in speed = (6 mi/hr - 25 mi/hr) = -19 mi/hr
Time for the change = 10 sec
|Acceleration| = (-19 mi/hr) / (10 sec) = -1.9 mile per hour per second
Admittedly, that's a rather weird unit.
Other units, perhaps more comfortable ones, are:
-6,840 mi/hr²
-2.79 feet/sec²
