How gravity holds the solar system together

Grade 6 Science Worksheet - Challenge Me

Circle the best answer.

1. 1.

   Outdoors, Esme's teacher swings a soft ball on a string to model a planet's orbit. In the model, what does the string stand for?

   • Nothing; it just keeps the ball tidy and in one place
   • A push from behind the planet
   • The planet's forward motion
   • The Sun's gravity pulling the planet inward
2. 2.

   the ball's circle shrinking as the string is pulled shorter. While the ball is swinging, the teacher slowly pulls the string shorter. How does the ball's trip around change, as Jun observes?

   • It goes around faster, like a closer planet
   • It goes around slower, like a farther planet
   • It stops circling and hangs still
   • It flies off in a straight line
3. 3.

   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?

   • The Sun pushing the planet away
   • Gravity switching off, so the planet moves in a straight line
   • The planet falling into the Sun
   • The planet speeding up in its orbit
4. 4.

   “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: wind in space steers them
   • Agree: motion alone keeps them circling
   • Disagree: they need rocket engines to keep them going around
5. 5.

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

   • Agree: we see the Sun cross the sky
   • Agree: Earth is the center of the solar system
   • Disagree: Earth spins daily and orbits the Sun yearly
   • Disagree: the Sun orbits Earth once a year, not once a day
6. 6.

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

   • Disagree: gravity holds the Milky Way's stars together
   • Disagree: galaxies are held together by wind between the stars
   • Agree: stars are held in place by light
   • Agree: galaxies are too big for gravity
7. 7.

   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
   • Slower than 47.4 km/s, since it is closer
   • Faster than 47.4 km/s
8. 8.

   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?

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

   “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?

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

    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?

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