The orbital period, [tex]P[/tex], of a planet and the planet's distance from the sun, [tex]a[/tex], in astronomical units is related by the formula [tex]P = a^{\frac{3}{2}}[/tex]. If Saturn's orbital period is 29.5 years, what is its distance from the sun?

A. 9.5 AU
B. 19.7 AU
C. 44.3 AU
D. 160.2 AU



Answer :

To determine Saturn's distance from the sun, denoted as [tex]\( a \)[/tex], given its orbital period [tex]\( P \)[/tex] of 29.5 years, we can use the relation:

[tex]\[ P = a^{\frac{3}{2}} \][/tex]

We need to solve for [tex]\( a \)[/tex] when [tex]\( P = 29.5 \)[/tex]. Here are the steps to find [tex]\( a \)[/tex]:

1. Formula Setup: We start with the equation:
[tex]\[ 29.5 = a^{\frac{3}{2}} \][/tex]

2. Isolate [tex]\( a \)[/tex]: To isolate [tex]\( a \)[/tex], we need to undo the exponent [tex]\(\frac{3}{2}\)[/tex]. To do this, we raise both sides of the equation to the power of [tex]\(\frac{2}{3}\)[/tex]. This is because:
[tex]\[ \left(a^{\frac{3}{2}}\right)^{\frac{2}{3}} = a^{\left(\frac{3}{2} \cdot \frac{2}{3}\right)} = a \][/tex]
So, applying this to both sides of the equation:
[tex]\[ \left(29.5\right)^{\frac{2}{3}} = a \][/tex]

3. Calculate [tex]\( a \)[/tex]: Given the true result, [tex]\(\left(29.5\right)^{\frac{2}{3}}\)[/tex] is approximately equal to 9.547. Thus:
[tex]\[ a \approx 9.547 \][/tex]

4. Round or approximate value: Generally, distances in astronomy are given to a few significant digits. Therefore, rounding 9.547 to the nearest value among the choices provided, we get approximately:
[tex]\[ a \approx 9.5 \text{ AU} \][/tex]

Therefore, Saturn's distance from the sun is approximately 9.5 AU.
The correct option is:
- [tex]\( \boxed{9.5 \text{ AU}} \)[/tex]