How gravity holds the solar system together

Grade 6 Science Worksheet - Challenge Me

Circle the best answer.

1. 1.

   The ball leaving the circle in a straight line after the string is let go. In the string model, what does letting go of the string stand for, by Kira's reasoning?

   • Gravity switching off, so the planet moves in a straight line
   • The Sun pushing the planet away
   • The planet speeding up in its orbit
   • The planet falling into the Sun
2. 2.

   “Orbit diagram from above, not to scale:” Luz's friend says planets keep orbiting because nothing in space can stop them, so gravity is not needed. Which response is best?

   • Disagree: without gravity they would move in straight lines
   • Agree: motion alone keeps them circling
   • Agree: wind in space steers them
   • Disagree: they need rocket engines to keep them going around
3. 3.

   A post says the Sun orbits Earth once a day. Milo checks it. Which response is best?

   • Disagree: Earth spins daily and orbits the Sun yearly
   • Disagree: the Sun orbits Earth once a year, not once a day
   • Agree: we see the Sun cross the sky
   • Agree: Earth is the center of the solar system
4. 4.

   Noah's cousin says gravity matters for planets but not for whole galaxies. Which response is best?

   • Agree: galaxies are too big for gravity
   • Disagree: galaxies are held together by wind between the stars
   • Disagree: gravity holds the Milky Way's stars together
   • Agree: stars are held in place by light

5. Read this first

   Use this

   Table (NASA Planetary Fact Sheet), with columns Planet, Distance (millions of km) and Orbit time (days), distance from the Sun and orbit time: Mercury 57.9 million km, 88.0 days; Venus 108.2 million km, 224.7 days; Earth 149.6 million km, 365.2 days; Mars 228.0 million km, 687.0 days.

6. 5.

   An object orbits the Sun at 180 million km. Using the NASA table, about how long does its orbit take, by Pia's reasoning?

   • Between 365 and 687 days
   • More than 687 days
   • Exactly 365 days
   • Less than 365 days, since it is farther out
7. 6.

   Mercury 47.4 km/s; Venus 35.0 km/s; Earth 29.8 km/s. A space probe orbits the Sun even closer than Mercury. About how fast does it move, judging from the NASA table, by Ren's reasoning?

   • Exactly 29.8 km/s, like Earth
   • Zero, since it is so near the Sun
   • Faster than 47.4 km/s
   • Slower than 47.4 km/s, since it is closer
8. 7.

   Orbit diagram from above, not to scale: Earth with the Moon's orbit far out and a satellite's orbit close in. The Moon orbits Earth in about 27.3 days at about 384,000 km. A satellite orbits much closer. How long does its trip probably take, says Tala?

   • Exactly 27.3 days, like the Moon
   • More than 27.3 days, since it is closer
   • Forever, since it is too close to move
   • Much less time than 27.3 days
9. 8.

   “not to scale” Suppose the Sun had more mass but stayed the same distance away. What would happen to its pull on Earth, by Zee's reasoning?

   • The Sun would push Earth away
   • The pull would be weaker
   • The pull would be stronger
   • No change, since distance decides it alone
10. 9.

    Earth with the Moon's present orbit and a larger dashed orbit. If the Moon were much farther from Earth, how would its orbit change, as Ari predicts?

    • Nothing about its orbit would change
    • A stronger pull and a quicker trip
    • It would leave in a straight line at once
    • A weaker pull, slower motion and a longer trip
11. 10.

    Long ago, a huge cloud of gas and dust pulled together to form the Sun and the planets. Which force did that, as Bo reads from NASA?

    • Earth's gravity, from the center of everything
    • No force; it happened by itself
    • Wind blowing the dust together
    • Gravity