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 Sun's gravity pulling the planet inward
   • 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 flies off in a straight line
   • It stops circling and hangs still
   • It goes around faster, like a closer planet
   • It goes around slower, like a farther planet
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
   • Gravity switching off, so the planet moves in a straight line
   • The planet falling into the Sun
4. 4.

   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
5. 5.

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

6. 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.

7. 6.

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

   • More than 687 days
   • Less than 365 days, since it is farther out
   • Exactly 365 days
   • Between 365 and 687 days
8. 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
   • Slower than 47.4 km/s, since it is closer
   • Faster than 47.4 km/s
   • Zero, since it is so near the Sun
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?

   • No change, since distance decides it alone
   • The pull would be stronger
   • The Sun would push Earth away
   • The pull would be weaker
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 weaker pull, slower motion and a longer trip
    • It would leave in a straight line at once
    • A stronger pull and a quicker 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?

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