Hyou ave you ever thought about the risks
you take when you travel? We have all
delays and traffic jams but have you ever heard about snakes? No? Well, here's a
story that will make you think twice the next time you fly.
It all started one day when a passenger boarded a flight in South Korea with a little
'something' extra in his luggage. However, he didn't declare what this something
extra was when he left South Korea,
When he arrived in Atlanta, USA, customs officer Christopher Hendericks checked
the man's luggage. To his surprise he found 30 snakes in bottles! He also found
some bird specimens in the bottles, and a special liquid with the snakes and birds
to preserve them.
Hendericks said, "I've found snakes before but what surprised me about this case
was how many there were. At least no passengers were hurt.” Even though the
reptiles and birds were not alive, there was still a problem. As the US Fish and
Wildlife Service stated, "It's possible that the dead snakes had poison in them. The
passenger even put scorpions in the snakes' mouths. So, we had to check all the
animal specimens in the bottles."
The airline did not release the name of the passenger. The police charged the man
with breaking the law twice, once for not declaring the strange contents of his
luggage and once for importing endangered species.
heard horror stories of missed flights, lost luggage, train составить вопросы по тексту
1.Найдите:
А) Амплитуду колебаний заряда.
В общем виде уравнение колебаний заряда q=qm*cos(ωt). Cопоставляя получаем qm=5*10^-4 Кл.
Б) Период. ω= 10^3π. Из ω = 2π/T, T=2π/ω=2π/(10^3π)=2*10^-3 c.
В) Частоту. Из υ=1/T, υ=1/(2*10^-3) =0,5*10^3 Гц= 500 Гц.
Г) Циклическую частоту. ω= 10^3π Гц= 3140 Гц.
2. Запишите уравнения зависимости напряжения на конденсаторе от времени:
Из формулы емкости конденсатора С=q/U имеем
u(t) = q(t)/C =
(5*10^-4cos(10^3πt))/(10*10^-12) = 0,5*10^8 cos(10^3πt):
и силы тока в контуре от времени: в общем виде i(t) =q(t) '=Imcos(ωt+π/2) - ток опережает колебания напряжения на конденсаторе на π/2, Im=ω*qm; Im=10^3π*5*10^-4=1,57 A.
Значит i(t) =1,57cos(10^3πt+π/2).