时间:2019-03-06 作者:英语课 分类:英语时差8,16


英语课

Pop quiz: you have a flat table and two billiard balls. You and your strong-armed friend each roll one of the balls off the table so they pass the edge at the same time, only his ball is traveling much faster than yours. Which one hits the ground first?


 


It’s one of the perennial 1 stumpers of physics class that, provided they both pass over the edge simultaneously 2, both balls will land at exactly the same time. In fact, no matter HOW fast the “fast” ball is moving, it will still fall at the same speed as the ball that just meanders 3 over the edge. Yes, even if the “fast” ball is fired out of a cannon 4, this will still hold true. The reason is that horizontal motion in no way affects vertical 5 motion: gravity acts on both the fast ball and the slow ball with the same force at all times. So while the fast ball lands much farther away, it doesn’t get to spend any more time in the air than the slow ball — or, for that matter, than any other ball moving at any speed in between.


 


In fact, the only thing that WILL make a difference in the landing times of the two balls is the curvature of the earth. If the fast ball moves SO fast that it’s able to get past the point where the ground starts to drop away significantly underneath 6 it, it then will indeed spend a longer time falling, but only because it will now have a greater distance to fall. And if you can generate the kind of energy required to produce this effect, you have just succeeded in putting your fast ball into orbit.



adj.终年的;长久的
  • I wonder at her perennial youthfulness.我对她青春常驻感到惊讶。
  • There's a perennial shortage of teachers with science qualifications.有理科教学资格的老师一直都很短缺。
adv.同时发生地,同时进行地
  • The radar beam can track a number of targets almost simultaneously.雷达波几乎可以同时追着多个目标。
  • The Windows allow a computer user to execute multiple programs simultaneously.Windows允许计算机用户同时运行多个程序。
曲径( meander的名词复数 ); 迂回曲折的旅程
  • The stream meanders slowly down to the sea. 这条小河弯弯曲曲缓慢地流向大海。
  • A brook meanders through the meadow. 一条小溪从草地中蜿蜒流过。
n.大炮,火炮;飞机上的机关炮
  • The soldiers fired the cannon.士兵们开炮。
  • The cannon thundered in the hills.大炮在山间轰鸣。
adj.垂直的,顶点的,纵向的;n.垂直物,垂直的位置
  • The northern side of the mountain is almost vertical.这座山的北坡几乎是垂直的。
  • Vertical air motions are not measured by this system.垂直气流的运动不用这种系统来测量。
adj.在...下面,在...底下;adv.在下面
  • Working underneath the car is always a messy job.在汽车底下工作是件脏活。
  • She wore a coat with a dress underneath.她穿着一件大衣,里面套着一条连衣裙。
学英语单词
active control tech nology
automation of cargo handling
axis of figure
bainitic transformation
bibliotherapist
blind bombing zone
Bromus magnus
bullock hearts
butt-jointed shell ring
Bükkzsérc
cadence detection
Callicarpa kochiana
chable
chondrogen
columnwise
combined arms team
computer network
contrary intention
corpora liberum pericardii
crosslevel
dar pahn
diphasic titration
dislocation mucleation
equidecomposability
expendable drone
external selection
extreme ultraviolet
fictious person
flat called
Francisco Jose de Goya
Gafac surfactant
give dosage form
ground robin
Herford
hey
isolation between inputs
Jerseytown
jimmying
Kadavu Island
kidney essence
king matker
legal discipline
locator variable
madioxytheria formosana
menformon
metal fuelled
mucolic acids
non-convex quadratic programming
nondelivered
North-West Frontier Province
ordnance engineering
os pharyngeum inferius
Osmoxylon
outlay for liquidation
pain receptor
panting girder
Peacekeeper missile
pick-up coil
pill maker
ply strain
plywood-covered
Porto Grande
pottled
predicting relation
Proxylide
Quipar, R.
rafter
rashie
registro
reticulated vein
shoaib
single row ball bearing with ring seal
six panel door
SL-SD
slip of pen
smooth approach
spectral source density
spray decoration
stalking horses
starter nozzle
stratified one-stage cluster sampling
strepsigonia diluta takamukui
subcutaenous calcareous granuloma
surface of translation
tension-active element
Teza
threa
thump-thump
track balance
transient radiation damage
true fibre
V die
venin-antivenin
ventilating tube
waveshape
within-participants design
woman on the beach
Yedineniya, Ostrov
yellowfins
ymesurid
Zeddam