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# M2 projectiles Watch

1. Are you allowed to quote the formula for the equation of the trajectory in the exam or do you have to derive it every time?

The old textbook I have quotes it for most problems but the Edexcel textbooks barely use it.
2. (Original post by solC)
Are you allowed to quote the formula for the equation of the trajectory in the exam or do you have to derive it every time?

The old textbook I have quotes it for most problems but the Edexcel textbooks barely use it.
You'd have to derive it if it's not in the formula booklet.
3. (Original post by RDKGames)
You'd have to derive it if it's not in the formula booklet.
Oh okay thanks
4. (Original post by solC)
Oh okay thanks
It takes about 2 lines to derive anyway,
5. (Original post by solC)
Oh okay thanks
There are exam questions where you have to derive the formula, but it's straightforward as Zacken said. You might as well learn the derivation.
6. (Original post by RDKGames)
You'd have to derive it if it's not in the formula booklet.
If that were the case, then presumably you would also have to derive
v^2 = u^2 + 2as
every time you used it.
7. (Original post by solC)
Are you allowed to quote the formula for the equation of the trajectory in the exam or do you have to derive it every time?

The old textbook I have quotes it for most problems but the Edexcel textbooks barely use it.
If Edexcel questions need it, they generally ask you to derive it.

Otherwise, you can quote it, but if so, please make sure that you've got it correct. An incorrect formula would mean that you'd lose all of the marks.
8. (Original post by tiny hobbit)
If that were the case, then presumably you would also have to derive
v^2 = u^2 + 2as
every time you used it.
It is that case.

You're expected to remember SUVAT equations and you're free to use them as they're on the spec, and they're the basis of Mechanics 2. That is not the case with the projectile one.
9. (Original post by RDKGames)
It is that case.

You're expected to remember SUVAT equations and you're free to use them as they're on the spec, and they're the basis of Mechanics 2. That is not the case with the projectile one.
We must agree to have different opinions on this.
10. I haven't seen it used in the new edexcel textbook, how does the formula help with projectiles questions?
11. What an absurdly specific formula to memorise. I despair.
12. (Original post by metrize)
I haven't seen it used in the new edexcel textbook, how does the formula help with projectiles questions?
Just saves a few lines, but i'm a lazy bugger so...
13. (Original post by metrize)
I haven't seen it used in the new edexcel textbook, how does the formula help with projectiles questions?
(Original post by mik1a)
What an absurdly specific formula to memorise. I despair.
It is occasionally useful, particularly if the angle of projection is unknown. If it is needed, Edexcel will generally ask you to derive it,as in June 2011. To do this you use s = ut horizontally and s = ut + 0.5at^2 vertically and then eliminate t.

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