Question

1. It takes time 8 min for light to reach from the sun to
the earth surface. If speed of light is taken to be
3 x 10^8 m s-, find the distance from the sun to the

earth in km.​

Answer 1

$\blue{\bold{\underline{\underline{Answer:}}}}$

$\green{\tt{\therefore{Distance=1.44\times 10^{11}\:m}}}$

$\orange{\bold{\underline{\underline{Step-by-step\:explanation:}}}}$

$\green{ \underline \bold{Given :}} \\ \tt: \implies Time \: taken(t) = 8 \: min \\ \\ \tt: \implies Speed \: of \: light(s) = 3 \times {10}^{8} \: m/s \\ \\ \red{ \underline \bold{To \: Find :}} \\ \tt: \implies Distance \: between \: earth \: and \: sun(D) =?$

• According to given question :

$\tt \circ \: Time = 8 \times 60 = 480 \: sec \\ \\ \bold{As \: we \: know \: that} \\ \tt: \implies Distance = Speed \times Time \\ \\ \tt: \implies Distance =3 \times 10^{8} \times 480 \\ \\ \tt: \implies Distance = 1440 \times {10}^{8} \: m \\ \\ \green{\tt: \implies Distance =1.44 \times {10}^{11} \: m} \\ \\ \bold{Alternate \: method} \\ \\ \tt \circ \: Acceleration = 0 \: m/{s}^{2} \\ \\ \tt \circ \: Time = 480 \: sec \\ \\ \tt: \implies s = ut + \frac{1}{2} {at}^{2} \\ \\ \tt: \implies s= 3 \times {10}^{8} \times 480 \\ \\ \green{\tt: \implies s=1.44 \times {10}^{11} \: m} \\ \\ \green{\tt \therefore Distance \: between \: sun \: and \: earth \: is \: 1.44 \times {10}^{8} \: m}$

Answer 2

Given ,

Time = 8 min or 480 sec

Speed = 3 × 10^(8) m/s

We know that , the relationship between speed and time

$\boxed{ \sf{Speed = \frac{Distance}{Time} }}$

Thus ,

Distance = 3 × 10^(8) × 480

Distance = 144 × 10^(9) m

Since , 1000 m = 1 km

Distance = 144 × 10^(9) / 1000

Distance = 144× 10^(6) km

∴The distance between sun and earth is 144 × 10^(6) km