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
   • Neap tides, since it is winter
   • Larger than usual spring tides
   • No change; distance has no effect
2. 2.

   A quarter Moon falls near apogee. What tides should a coast expect, by Jun's reading?

   • No tides
   • Large tides, since the Moon is far
   • Strong spring tides
   • Smaller than usual neap tides

3. Read this first

   Monday high tides (model data)

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

4. 3.

   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 3:50 p.m.
   • About 4:15 p.m.
   • About 2:35 p.m.
   • About 3:25 p.m.
5. 4.

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

   • Agree: spring weather raises the sea
   • Disagree: they come twice a month, at new and full Moon
   • Disagree: they come at the quarter Moons
   • Agree: the name says so
6. 5.

   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)?

   • Agree: the Sun pulls on Earth 177 times harder
   • Disagree: the Sun has no effect on tides
   • Disagree: tidal force falls with distance cubed; the Sun's is about half
   • Agree: more mass means bigger tides
7. 6.

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

   • Agree: the Moon pulls one side
   • Agree: the far side has no bulge
   • Disagree: there are four high tides
   • Disagree: there are two bulges, so most coasts get two highs
8. 7.

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

   • 1/8 as strong
   • 1/2 as strong
   • 1/4 as strong
   • Twice as strong
9. 8.

   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 0.37 times
   • About 1.46 times
   • About 1 time; they are equal
   • About 2.7 times
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 diurnal tide
    • A mixed semidiurnal tide
    • A neap tide
    • A semidiurnal tide
11. 10.

    World map with continents blocking ocean bulges. Why do some coasts not get two equal high tides a day, by Bo's reading (NOAA)?

    • The Moon skips some coasts
    • Those coasts are in a different season
    • Continents block the bulges, so each basin has its own pattern
    • The Sun cancels tides on some coasts