<span>The last main subatomic particle to be discovered was the
antihelium-4. It was discovered on 2011
and it is measured and produces through the STAR detector. The Antihelium-4 was discovered accidentally
when an experiment was conducted. It is
also the first particle that was discovered by the means of experiment.</span>
The answer is so that everyone is measuring the same distance and counting that distance as the same everywhere. one example from real life why it is important to use standard units is the loss of the NASA mars orbiter. some people decided that the units were to be in metric and others thought that the units were in imperial (english) system. so the orbiter was lost.
let's eliminate some choices
A. to allow for consistientcy with measurement data:
not really, just make sure the instruments are accurate.
B. to use tools marked in customary units: this could be true because a custom is something that is accepted in a wide area and if it is standard, then it is customary so b is the answer
C. so they can keep measurement data secret: nope
D. to record with easier abbreviations: not really
the answer is B
Answer:
F = k q1 q2 / r^2
r^2 = k q1 q2 / F = 9E9 * 4E-5 * 10.8E-5 / 4
r^2 = 9 * 4 * 10.8 / 4 * E-1 = 9.72 m^2
r = 3.12 m
Suppose rowing speed is V km/s.
So, upstream speed = V-2
Downstream speed = V+ 2
Total time is taken 3 h 20 min to cover up and down journey of 5 km.
So, total time = upstream time + downstream time
and 
, we take only positive velocity.
Thus, the the rowing speed of the crew in still water is 1 km/s.
