Newton's law of universal gravitation

Answer Key - Grade 11 Science Worksheet - Challenge Me

Circle the best answer, or write your answer on the line.

1. 1.

   Earth's mass is 5.9722 × 10²⁴ kg and its radius is 6371 km. With G = 6.674 × 10⁻¹¹ N·m²/kg², what is g at 400 km above the surface, to the nearest hundredth, Ari?

   8.69 N/kg
2. 2.

   Earth's mass is 5.9722 × 10²⁴ kg and its radius is 6371 km. With G = 6.674 × 10⁻¹¹ N·m²/kg², what is g at 6371 km above the surface, to the nearest hundredth, Bo?

   2.45 N/kg
3. 3.

   Earth's mass is 5.9722 × 10²⁴ kg and its radius is 6371 km. With G = 6.674 × 10⁻¹¹ N·m²/kg², what is g at 1000 km above the surface, to the nearest hundredth, Esme?

   7.34 N/kg
4. 4.

   The distance between two bodies halves. What happens to the gravitational force, Jun?

   • It is 4 times as big
   • It doubles
   • It halves
5. 5.

   Both masses double, and the distance between them doubles too. What happens to the force, Kira?

   • It is 8 times as big
   • It stays the same
   • It doubles
6. 6.

   The distance between two bodies becomes 10 times as large. What fraction of the force is left, Luz?

   • One-tenth
   • One-hundredth
   • One-thousandth
7. 7.

   Milo says there is no gravity at a satellite's height of 400 km. Agree or disagree?

   • Disagree: g there is still about 8.7 N/kg
   • Agree: gravity stops in space
   • Agree: satellites float, so nothing pulls them
8. 8.

   Noah says Earth pulls harder on the Moon than the Moon pulls on Earth. Agree or disagree?

   • Disagree: the pulls are equal and opposite
   • Agree: Earth has more mass
   • Agree: Earth is closer to the Sun
9. 9.

   Pia says a heavy box and a light box near each other pull on each other with different forces. Agree or disagree?

   • Agree: the light box pulls harder
   • Agree: the heavy box pulls harder
   • Disagree: the two pulls are equal

10. Read this first

    Earth, Mars and the Moon (NASA fact sheets)

    Body	Mass (10²⁴ kg)	Mean radius (km)
    Earth	5.9722	6371
    Mars	0.64169	3389.5
    Moon	0.07346	1737.4

11. 10.

    Using the table, Mars has about one-ninth of Earth's mass, but more than one-ninth of its surface gravity. Why, Tala?

    • Mars spins faster than Earth
    • Its radius is smaller, so its surface is closer to its center
    • Mars's gravity doesn't depend on its mass