Why the tides rise and fall

Grade 9 Science Worksheet - Challenge Me

Circle the best answer.

1. 1.

   Early one January, the full Moon falls near perigee. What tides should a coast expect, by Esme's reading?

   • Small tides, since the Moon is close
   • Larger than usual spring tides
   • No change; distance has no effect
   • Neap tides, since it is winter

2. Read this first

   Monday high tides (model data)

   Tide	Time
   high	3:00 a.m
   high	3:25 p.m

3. 2.

   A beach had high tides at 3:00 a.m. and 3:25 p.m. on Monday. About when is Tuesday's afternoon high tide, by Kira's math?

   • About 3:25 p.m.
   • About 4:15 p.m.
   • About 3:50 p.m.
   • About 2:35 p.m.
4. 3.

   Moon-phase calendar with spring tides marked. Luz's friend says spring tides happen in the spring. Which response is best?

   • Agree: the name says so
   • Disagree: they come twice a month, at new and full Moon
   • Disagree: they come at the quarter Moons
   • Agree: spring weather raises the sea
5. 4.

   Tidal force ∝ mass ÷ distance³. Milo's cousin says the Sun is far bigger, so it must cause most of the tides. Which response is best (NOAA)?

   • Disagree: the Sun has no effect on tides
   • Agree: more mass means bigger tides
   • Agree: the Sun pulls on Earth 177 times harder
   • Disagree: tidal force falls with distance cubed; the Sun's is about half
6. 5.

   Noah's friend says there should be just one high tide a day, on the side facing the Moon. Which response is best (NOAA)?

   • Disagree: there are two bulges, so most coasts get two highs
   • Disagree: there are four high tides
   • Agree: the Moon pulls one side
   • Agree: the far side has no bulge
7. 6.

   Tidal force ∝ 1 ÷ distance³. If the Moon were twice as far away, how strong would its tidal force be, by Pia's math?

   • 1/4 as strong
   • Twice as strong
   • 1/8 as strong
   • 1/2 as strong
8. 7.

   Spring ≈ 1 + 0.46; neap ≈ 1 − 0.46. In a simple model, spring tides ≈ Moon + Sun (1 + 0.46) and neap tides ≈ Moon − Sun (1 − 0.46). About how many times larger is a spring tide, by Ren's math?

   • About 1.46 times
   • About 2.7 times
   • About 1 time; they are equal
   • About 0.37 times
9. 8.

   Tidal force ∝ mass ÷ distance³. A moon with twice the mass, at the same distance, would raise tides how large, by Tala's math?

   • 8 times as large
   • 4 times as large
   • Unchanged
   • Twice as large
10. 9.

    NOAA: many Gulf of Mexico coasts get one high and one low tide a day. What is that pattern called, by Zee's reading?

    • A neap tide
    • A mixed semidiurnal tide
    • A diurnal tide
    • A semidiurnal tide
11. 10.

    A coast gets two high tides a day, but one is much higher than the other. What is that pattern called, by Ari's reading (NOAA)?

    • A mixed semidiurnal tide
    • A diurnal tide
    • A semidiurnal tide, since heights do not count
    • A spring tide