Answer
given,
Echo time = t = 1000 s
speed = ?
[tex]v = \dfrac{d}{t}[/tex]
a) speed of electromagnetic wave
[tex]c = \dfrac{d}{t}[/tex]
wave travels Venus two time
[tex]c = \dfrac{2d}{t}[/tex]
[tex]d = \dfrac{ct}{2}[/tex]
[tex]d = \dfrac{3 \times 10^8\times 1000}{2}[/tex]
d = 1.5 x 10¹¹ m
b) now, echo time
[tex]c = \dfrac{2d}{t}[/tex]
[tex]t = \dfrac{2d}{c}[/tex]
[tex]t = \dfrac{2\times 75}{3 \times 10^8}[/tex]
t = 5 x 10⁻⁷ s
