时间:2018-12-31 作者:英语课 分类:英语听力文摘 English Digest


英语课

   In the 17th century, the French scientist Pierre Gassendi knew that light traveled faster than sound. When a gun fired far away, he could see the flash of gunshot long before he heard the report.


 
  Gassendi tried to measure the speed of sound by clocking the time that elapsed between the flash and the gunshot. Knowing the exact distance the gun was from him, he calculated that sound traveled through air at over 1,000 miles per hour. This figure is too high, though. Can you guess why?
 
  The problem was that Gassendi relied on his own reaction time, making his measurement higher than it should have been.

  In 1864, another French scientist, Henri Regnault, devised a way to measure the speed of sound automatically, again by using a gun, but without relying on human reaction time. Regnault covered a rotating cylinder 1 with paper, and positioned a pen to draw a line as it turned. Next, he wired the pen to two electrical circuits, placing one in front of the gun some distance away, and the second near the cylinder, threaded through a diaphragm sensitive to sound.
 
  When the gun fired, the first circuit broke, making the pen jump to a new position on the rotating cylinder. When the sound reached the diaphragm by the cylinder, the pen jumped back to its original position. Because Regnault knew how far the gun was from the cylinder and how fast the cylinder turned, he calculated that sound travels through air at 750 miles per hour, quite close to the speed physicists 2 accept today.

n.圆筒,柱(面),汽缸
  • What's the volume of this cylinder?这个圆筒的体积有多少?
  • The cylinder is getting too much gas and not enough air.汽缸里汽油太多而空气不足。
物理学家( physicist的名词复数 )
  • For many particle physicists, however, it was a year of frustration. 对于许多粒子物理学家来说,这是受挫折的一年。 来自英汉非文学 - 科技
  • Physicists seek rules or patterns to provide a framework. 物理学家寻求用法则或图式来构成一个框架。
学英语单词
AC45
acceptance of persons
actual authority
address identification
alternating current distribution
aminosugars
amoebous
anaerobic glycolysis
antural-circulation steam generator
arithmetical continuum
ask price
b.d.i.
b.o.q.
batallion
bellows-operated pilot valve
benthonic plaukton
Borassoideae
brickshaped
cancel status word
carbonated spring(carbon dioxide spring)
carboxybiotin
chaotic inflation
Chinese technology
chowing down
CI-719
concrete workability
controlled burn
conveyance of production payment
device address
dictation machines
Dirico
domestictraffic
early soil
economic theoreticians
educational managerialics
electroly
eligible corporate bond for collateral for a loan
emergency pulses
exercise limit
experimental structural geology
fiese
flat riser
fore-inclined
front and rear
garden city
genizah
gibco-brl
Gurye-gun
haveing
idler carrier
in patches
increment due to increased light
insured amount
lightning flash-over
literary sketch
lookforward
methylol
molded piece
Monozon
nailery
no pain
nonchromogenic bacterium
o.t.
oscillating separator
overcontributions
pain sense
panter
partial desiccation
pattern maker's lathe
permuted indexes
pestilence-wort
petrol garage
Phenoverm
pilot hole diameter
piston heat set screw
postponement
psychogenic headache
random - access memory
ranulas
re-crossed
reseated
rough-lookings
sadly
Santa Maria Novella
Saxifraga lepidostolonosa
side-draw tray
stainch
stop someone in mid career
submarine base
susperior aurioular muscle
systematic screw series experiments
throw sth in sb's teeth
thynnic acid
to one ear
transmitting directivity
Tsunemi
tube seam
Urds
vacuum control modulator valve
virtopsies
virtual partitioned access method
walu