eres, the largest asteroid known, has a mass of roughly 8.7 x 10^20 kg If Ceres passes within 14,000 km of the

spaceship in which you and your dog are traveling, what force does it exert on your dog? The mass of your dog is

30 kg. (Treat your dog and the asteroid as point objects.)

1 answer

To calculate the gravitational force exerted by Ceres on your dog, we can use Newton's law of universal gravitation:

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

where:

  • \( F \) is the force between the two objects,
  • \( G \) is the gravitational constant, approximately \( 6.674 \times 10^{-11} , \text{N m}^2/\text{kg}^2 \),
  • \( m_1 \) is the mass of Ceres,
  • \( m_2 \) is the mass of your dog,
  • \( r \) is the distance between the centers of the two objects.

Given:

  • Mass of Ceres, \( m_1 = 8.7 \times 10^{20} , \text{kg} \)
  • Mass of your dog, \( m_2 = 30 , \text{kg} \)
  • Distance, \( r = 14,000 , \text{km} = 14,000,000 , \text{m} \)

Now we can substitute these values into the equation:

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

Substituting in the values:

\[ F = 6.674 \times 10^{-11} \frac{(8.7 \times 10^{20})(30)}{(14,000,000)^2} \]

Calculating the denominator:

\[ (14,000,000)^2 = 1.96 \times 10^{14} , \text{m}^2 \]

Now substituting back into the equation:

\[ F = 6.674 \times 10^{-11} \frac{(8.7 \times 10^{20})(30)}{1.96 \times 10^{14}} \]

Calculating the numerator:

\[ (8.7 \times 10^{20})(30) = 2.61 \times 10^{22} \]

So we have:

\[ F = 6.674 \times 10^{-11} \frac{2.61 \times 10^{22}}{1.96 \times 10^{14}} \]

Now, calculating the fraction:

\[ \frac{2.61 \times 10^{22}}{1.96 \times 10^{14}} \approx 1.33 \times 10^{8} \]

Now substituting back to find \( F \):

\[ F = 6.674 \times 10^{-11} \cdot 1.33 \times 10^{8} \]

Calculating the final result:

\[ F \approx 8.88 \times 10^{-3} , \text{N} \]

Thus, the force exerted by Ceres on your dog when it passes within 14,000 km is approximately:

\[ \boxed{0.00888 , \text{N}} \]