Two asteroids are 50,000 m apart. One has a mass of [tex]\(5 \times 10^8 \, \text{kg}\)[/tex]. If the force of gravity between them is [tex]\(8.67 \times 10^{-2} \, \text{N}\)[/tex], what is the mass of the other asteroid?

A. [tex]\(6.5 \times 10^9 \, \text{kg}\)[/tex]

B. [tex]\(7.2 \times 10^9 \, \text{kg}\)[/tex]

C. [tex]\(5.0 \times 10^8 \, \text{kg}\)[/tex]

D. [tex]\(5.8 \times 10^8 \, \text{kg}\)[/tex]



Answer :

Certainly! Let's solve this problem step-by-step using the law of universal gravitation.

1. Identify the given values:
- Gravitational constant, [tex]\( G = 6.67430 \times 10^{-11} \, \text{m}^3 \, \text{kg}^{-1} \, \text{s}^{-2} \)[/tex]
- Mass of the first asteroid, [tex]\( m_1 = 5 \times 10^8 \, \text{kg} \)[/tex]
- Distance between the asteroids, [tex]\( r = 50,000 \, \text{m} \)[/tex]
- Gravitational force between them, [tex]\( F = 8.67 \times 10^{-2} \, \text{N} \)[/tex]

2. Recall the formula for gravitational force:
[tex]\[ F = G \frac{m_1 \cdot m_2}{r^2} \][/tex]
where:
- [tex]\( F \)[/tex] is the gravitational force,
- [tex]\( G \)[/tex] is the gravitational constant,
- [tex]\( m_1 \)[/tex] and [tex]\( m_2 \)[/tex] are the masses of the two objects,
- [tex]\( r \)[/tex] is the distance between them.

3. Rearrange the formula to solve for the mass of the second asteroid [tex]\( m_2 \)[/tex]:
[tex]\[ m_2 = \frac{F \cdot r^2}{G \cdot m_1} \][/tex]

4. Substitute the given values into the formula:
[tex]\[ m_2 = \frac{8.67 \times 10^{-2} \, \text{N} \cdot (50,000 \, \text{m})^2}{6.67430 \times 10^{-11} \, \text{m}^3 \, \text{kg}^{-1} \, \text{s}^{-2} \cdot 5 \times 10^8 \, \text{kg}} \][/tex]

5. Calculate the numerator:
- Distance squared: [tex]\( (50,000)^2 = 2.5 \times 10^9 \, \text{m}^2 \)[/tex]
- Force times distance squared: [tex]\( 8.67 \times 10^{-2} \times 2.5 \times 10^9 = 2.1675 \times 10^8 \)[/tex]

6. Calculate the denominator:
[tex]\[ 6.67430 \times 10^{-11} \times 5 \times 10^8 = 3.33715 \times 10^{-2} \][/tex]

7. Divide the numerator by the denominator to find [tex]\( m_2 \)[/tex]:
[tex]\[ m_2 = \frac{2.1675 \times 10^8}{3.33715 \times 10^{-2}} = 6.49506315269017 \times 10^9 \][/tex]

8. Express the final result with the correct significant figures:
[tex]\[ m_2 \approx 6.5 \times 10^9 \, \text{kg} \][/tex]

Therefore, the correct answer is:

A. [tex]\( 6.5 \times 10^9 \, \text{kg} \)[/tex]

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