Question
(a) State, in order, the names of the three planets closest to the Sun.
Closest to the Sun
Furthest from the Sun \([2]\)
(b) Define a light-year. [2]
(c) Jupiter is \(780000000000 \mathrm{~m}\left(7.8 \times 10^{11} \mathrm{~m}\right)\) from the Sun.
The speed of light is \(300000000 \mathrm{~m} / \mathrm{s}\left(3.0 \times 10^8 \mathrm{~m} / \mathrm{s}\right)\).
Calculate the time for light to travel from the Sun to Jupiter.
$
\text { time }=
$
[Total: 6]
▶️Answer/Explanation
Ans:
(closest to Sun) Mercury
Venus
(furthest from Sun) Earth
(b) distance
travelled by light (in the vacuum of space) in one year
(c) $
2.6 \times 10^3(\mathrm{~s}) \text { OR } 2600(\mathrm{~s})
$
time \(=\) distance \(\div\) speed OR \(7.8 \times 10^{11} \div 3.0 \times 10^8\)
OR \(780000000000 \div 300000000\)