Two spaceships of mass [tex]300,000 \, \text{kg}[/tex] are [tex]250 \, \text{m}[/tex] apart. What is the force of gravity between them?

[tex]\left(G = 6.67 \times 10^{-11} \, \text{N} \cdot \text{m}^2 / \text{kg}^2\right)[/tex]

A. [tex]2.40 \times 10^{-2} \, \text{N}[/tex]
B. [tex]9.6 \times 10^{-5} \, \text{N}[/tex]
C. [tex]8.00 \times 10^{-8} \, \text{N}[/tex]
D. [tex]7.23 \times 10^{-6} \, \text{N}[/tex]



Answer :

To calculate the force of gravity between the two spaceships, we will use Newton's law of universal gravitation, which states that the gravitational force [tex]\( F \)[/tex] between two masses [tex]\( m_1 \)[/tex] and [tex]\( m_2 \)[/tex] separated by a distance [tex]\( r \)[/tex] is given by:

[tex]\[ F = G \frac{m_1 m_2}{r^2} \][/tex]

where:
- [tex]\( G \)[/tex] is the gravitational constant, [tex]\( 6.67 \times 10^{-11} \, \text{N} \cdot \text{m}^2/\text{kg}^2 \)[/tex],
- [tex]\( m_1 \)[/tex] is the mass of the first spaceship, [tex]\( 300,000 \, \text{kg} \)[/tex],
- [tex]\( m_2 \)[/tex] is the mass of the second spaceship, [tex]\( 300,000 \, \text{kg} \)[/tex],
- [tex]\( r \)[/tex] is the distance between the two spaceships, [tex]\( 250 \, \text{m} \)[/tex].

Following these steps:

1. Substitute the given values into the formula:

[tex]\[ F = 6.67 \times 10^{-11} \, \text{N} \cdot \text{m}^2/\text{kg}^2 \times \frac{300,000 \, \text{kg} \times 300,000 \, \text{kg}}{(250 \, \text{m})^2} \][/tex]

2. Calculate the product of the masses:

[tex]\[ 300,000 \times 300,000 = 90,000,000,000 \, \text{kg}^2 \][/tex]

3. Calculate the square of the distance:

[tex]\[ (250 \, \text{m})^2 = 62,500 \, \text{m}^2 \][/tex]

4. Substitute these results back into the formula:

[tex]\[ F = 6.67 \times 10^{-11} \, \text{N} \cdot \text{m}^2/\text{kg}^2 \times \frac{90,000,000,000 \, \text{kg}^2}{62,500 \, \text{m}^2} \][/tex]

5. Perform the division in the fraction:

[tex]\[ \frac{90,000,000,000}{62,500} = 1,440,000 \][/tex]

6. Multiply by the gravitational constant:

[tex]\[ F = 6.67 \times 10^{-11} \times 1,440,000 \, \text{N} \][/tex]

7. Calculate the final result:

[tex]\[ F \approx 9.6048 \times 10^{-5} \, \text{N} \][/tex]

Therefore, the force of gravity between the two spaceships is [tex]\( 9.6 \times 10^{-5} \)[/tex] N, which corresponds to option B.