JIFFY - Dimensional Analysis?

Question

The American physical chemist Gilbert Newton Lewis proposed a unit of time called the "jiffy". According to Lewis, 1 jiffy = the time it takes light to travel one centimeter. (a) If you perform a task in a jiffy, how long has it taken in seconds? (b) How many jiffys are in one minute? (Use the fact that the speed of light is approximately 2.9979 x 10^8 m/s.)

Answer 1

All you need to solve this is to determine the length of a jiffy in seconds. Since velocity = length / time, then time = length / velocity.

1 jiffy = 0.01 m / 2.9979e8 m/s = 3.3357e-11 seconds

Answer 2

This is cute, but it points out a major issue in physics...technical people who make up definitions. The scientists, mathematicians, engineers, and such who are brilliant at their work are absolutely lousy as lexicographers. In being lousy at defining terms, they manage to make already difficult subjects even more difficult subjects to learn.

Case in point, when I studied undergrad physics, we called the motion of a wave "cycles per second." That had meaning because it simply meant the transverse wave pattern cycled through so-many wavelengths in a second. Now they call it Herz and that has no physical meaning whatsoever. It's like calling kilometers per hour a Hawking.

Dimensional/units analysis is best served by sticking to the SI units...kg, meter, sec...for example. Jiffy, Herz, Newton, and all those other meaningless terms have no place in dimensional analysis.

Sorry this does not answer your question, but it is something that has to be said.

Answer 3

2/100*3*10^8 sec=1 jiffy
6*10^-11 sec= 1jiffy
6*10^-11/60 min= 1jiffy
10^12 min= 1jiffy

Answer 4

Speed of light in cm/sec=2.9979X10^10
1 jiffy=1/2.9979X10^10 sec
1 sec=2.9979X10^10 jiffys
1minute=60sec=60X2.9979X10^10 secs