A Projectile Fired At A 45 Degree Angle

[Cipherflak]

6=9.8t^2*(100/0.7071t)*0.7071

we just told you that you should have a plus in there, not a multiplication!

you do something wrong when you insert the substitution.

 

[miniradman]

Ah, found the problem,

s = ut+(1/2) at^2

I used this formula and I got the right answer... thanks anyway guys

 

[Cipherflak]

well you can't solve this problem with only one equation.

 

[miniradman]

Yep, I used that s=ut+1/2 at^2 for both the horizontal and vertical components ;)

 

[Cipherflak]

With 0 acceleration in the horionztal I take it. That's actually what I said in my equations.

 

[miniradman]

Yes true, but there was still no 1/2 in either of them.

I tried to work it out without the 1/2 and I kept getting a cubic which cannot be solved. The one half made heaps of difference ;)

 

[Cipherflak]

OUCH! i simply forgot to write down the half! Pretty amazing that no-one noticed! Sorry about that, dude! :)(the half actually appears from taking the anti-derivative of of t, resulting in 0.5(t)^2.)

 

[miniradman]

I've haven't learned about anti-derivatives yet. But I see what you have done there.

Its not a problem mate, everyone makes mistakes ;)

 

[Cipherflak]

Yup. Those 4 basic equations of motions is what you use when you start out with physics, but you see clearly where they naturally come from first when you learn about derivates and integration.

:)