The speed of radio waves is 297 600 km per second. How much time is needed for the ratio impulse to travel from a station to a radio if the distance between them is 1280 km? Express the answer in scientific notation.
Answers
Answer:Any radio wave is moving at the speed of light, regardless of the frequency, so the frequency should be superfluous information.
The speed is light is close to
300
,
000
k
m
s
I take the distance you are given, to be
8.2
⋅
10
7
k
m
(since
8.2
⋅
107
k
m
doesn't make good sense - it's less than 1000 km)
i.e.
82
,
000
,
000
km.
Before we actually compute this, we can notice that this is a little more than half the distance of the earth from the sun (150 mill. km), a distance the light uses 500 sek. = 8 min 20 sec. to travel, so we should get about
4
1
2
min for the radio wave to reach Mars from the earth.
Actual calculation:
82
,
000
,
000
k
m
300
,
000
k
m
s
=
820
3
s =
273.3
s
As the distance is given with 2 significant figures, we round this off to 270 sek = 4 min 30 se
Explanation: