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?

   • The Sun's gravity pulling the planet inward
   • Nothing; it just keeps the ball tidy and in one place
   • A push from behind the planet
   • The planet's forward motion
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 slower, like a farther planet
   • It flies off in a straight line
   • It goes around faster, like a closer planet
   • It stops circling and hangs still
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
   • The planet speeding up in its orbit
   • The planet falling into the Sun
   • Gravity switching off, so the planet moves in a straight line
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: they need rocket engines to keep them going around
   • Disagree: without gravity they would move in straight lines
   • Agree: wind in space steers them
   • Agree: motion alone keeps them circling
5. 5.

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

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

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

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

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

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

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

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