Question

Spring tides are stronger than average tides and neap tides are weaker than average tides. Which type of planetary alignment would you expect to result in a normal tide?
a. Sun, Moon, and Earth aligned with the Sun and Moon on opposite sides of the Earth
b. Sun, Moon, and Earth aligned with the Sun and Moon on the same side
c. Sun, Moon, and Earth form a right angle
d. Sun, Moon, and Earth form a 45 degree angle

Answer 1

The tides are caused by the pull of gravity on the water by the moon and the sun. The moon and the sun produce two different gravitational fields, both of which pull on the water.

When the two gravitational fields are both tugging from the same side of the earth, the pull is strongest. But when they are tugging from opposite sides, their attractions somewhat cancel each other out, resulting in a weaker influence on the water.

Drawing sketches of these two scenarios will probably help you sort this out.

Answer 2

oh awesome, so does that mean it would be a because they cancel each other out which makes it normal?

Answer 3

No, sorry. I mean that when the moon and the sun are on opposite sides of the earth, the gravitational force from the moon pulls the water one way. But the gravitational pull from the sun, on the opposite side, pulls the water back the other direction. So in that sense the two gravitational fields cancel out the other's effect.

Answer 4

Im confused. Is there such thing as the sun moon and earth making a 45 degree angle?

Answer 5

Yes - there is. Any three points in space can make an angle. But that's not the situation I'm talking about...

Answer 6

okay so what is that situation do to the tides, just to understand..

Answer 7

Well the tides are caused by the influence of the moons and the suns gravity. And the effects had by the suns and moons gravity depends on where the sun and the moon are, relative to the earth.

For example, when the sun and moon are like this - both on the same side of the earth - their gravity both pulls the water in the same direction.



But when the sun and the moon are on opposite sides of the earth, their gravity pulls the water in opposite directions.

Answer 8

ok so opposite is strong or weak?

Answer 9

When both gravitational fields are pulling in different directions (i.e., when they are opposite), the effect of the sun cancels out some of the effect of the moon. Basically the moon would pull the water to the right, in the picture above, and then the sun would pull it a little way back to the left. That is the case that opposite corresponds to.

Answer 10

ok so its not d, or a, right?

Answer 11

Correct. :D

Answer 12

ok so its not c because perpendicular is when there are neap tides

Answer 13

and neap tides is weak

Answer 14

No, I think it is C.

Yes, the neap tides are the weak ones. When the sun and the moon are on opposite sides of the earth. And it is asking you for the average tides, the ones absolutely intermediate between the case where the Sun and Moon are on opposite sides (neaps/weak) and the case where they are on the same side (strong/spring).

Answer 15

On my review sheet it says this about tides:
Which type of tide has the greatest range between the high and low tide marks?
Spring

What type of tide has two high tide and two low tide periods in a single day?
Semidiurnal

What do we call it when the water flows out from the shore?
Ebb

Spring Tide: When the moon and sun are both aligned with the Earth, the solar and lunar tides have an additive/greater effect. **Quiz error alert** Spring tides = not just in the season

Neap Tide: When they are perpendicular to each other, the solar and lunar tides negotiate, counteract each other.

Answer 16

Your review sheet is correct about the spring tide, but incorrect about the neap tide. The solar and lunar tides can only counteract each other if they come from opposite directions, not perpendicular directions.

And I have to ask, is this question from a quiz that you are taking?

Answer 17

yea but I learned it that way. No its a review question

Answer 18

Those were questions too

Answer 19

OK, cool. :)

Answer 20

Okay, so I even see on other resource sites that
Spring tides - is when tides are high
Neap tides - is when tides are low

Answer 21

even the dictionary says that: http://www.thefreedictionary.com/neap+tide
Im so confused.. I'm so sorry

Answer 22

I am sorry that you are confused.

And I agree. Spring tides are when they are high. Neaps are when they are low.

Answer 23

Okay, its not your fault though.. So, its correct then what happens to the sun moon and earth when there are normal tides?

Answer 24

The sun, the moon and the earth form a 90 degree angle. In other words, they are perpendicular to each other.

Answer 25

ok...

Answer 26

But what your saying is that neap tides are normal tides, because Neap Tide: When they are perpendicular to each other..

Answer 27

No, I don't mean that neap tides are normal tides. I mean that neap tides are the really low tides, when the sun and moon are opposite to each other.

Answer 28

yes true. okay. so elimination time ;) : its not c or d

Answer 29

D is certainly out.

But normal tides are when the sun, earth and moon are at a right angle. Just like in the third picture.

Answer 30

yes, but perpendicular is a right angle. and right angles are neap tides, low tides; its asking normal tides. Right?

Answer 31

Neap tides are low tides. Neap tides/low tides are opposite angles. Not perpendicular angles. Perpendicular angles are normal tides. And yes, it is asking about normal tides.

Answer 32

thats not what i learn and what it says on my review sheet

Answer 33

Which is why I think your review sheet is wrong.

Answer 34

ok wait

Answer 35

this is what I learned in class. This is a slide from that same review sheet. It says "perpendicular'' for neap tides its shows spring, since its next to it, but she even explained that its perpendicular, the top picture is a neap tide.

Answer 36

If that's what your school wants, follow the review sheet. At the end of the day, 'correct' is how your school defines things. But I don't think their definition of correct is realistic in context of how things really are in the world.

I am sorry for the confusion.

Answer 37

its okay. thats why im so confused half the time.. anyway so it would be b?

Answer 38

As I said, I don't know why your school choses to define correct the way it has in this context. It is not a decision I agree with. If you don't understand it (and in my opinion you have every reason to not understand it), it is they whom you should ask for an explanation, not me. I'm sorry.

Answer 39

Okay, Thank you so much for helping me out! I understand. :D

Answer 40

Thanks for your patience. I appreciate how trying this must have been for you.