Rocket Launch HELP!! asap (1 Viewer)

sickdog12

sickdog12

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i need help with this practical i have to do on a rocket launch..:bomb:

i just cant grasp projectile motion...everytime i look at it my head spins lol

im asked to

1) calculate the net force and hence the acceleration of the rocket. Determine the "g" forces involved in the rocket launch.
2) Using the elevation method determine the maximum height.
3) Using the projectile motion method, determine the maximum height
4) Comment on answers 2 and 3
5) write a conclusion

2 rockets: a)0.062kg ........ 0.608 N
b)0.071kg ........ 0.697 N

and we were also given the value of 6N of thrust!
:confused: please someone help!! anything u can give!!
 
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xiao1985

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g force is easy... just find force applied and get that divide by mg and you have your g force...

question 2 and 3 are weird... you will need to assume that the thrust is momentary... then i suppose you have two ways to do the question:

u2 = v2 + 2as
and find the max height

v = u + at
find the time which it takes to max height and use
s = ut + 1/2 a t 2

4) answer 2 and 3 should be the same

5) is up to you...
 
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LoneShadow

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Why they have so many dumb equations for projectile motions beats me. All u need to know is that a = d^2x/dt^2.
 
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xiao1985

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aww my lonelyshadow friend.... not everyone does 4u and can manipulate the equation like the back of their hand...
 
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LoneShadow

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lol. Hey duckie.

you don't need 4u maths for that. I tried memorising those formulae. Never was able to do so. Instead of wasting so much energy memorising, they could teach the calculus method. Did the projectile question in HSC exam in about 30 seconds maximum :p
 
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LoneShadow

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f3nr15 said:
We can use calculus in the external Physics exam ?

Then I can use Vind = - dΦ/dt then for induced emf then !
Click to expand...
Don't lose marks by listening to me. I don't know whether they gave me any marks or not. :p
 
alcalder

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f3nr15 said:
We can use calculus in the external Physics exam ?

Then I can use Vind = - dΦ/dt then for induced emf then !
Click to expand...
Why not? Of course you can. Using the tools you have to hand to reach the right answer is never wrong. Just because they don't teach calculus or encourage it in physics (anymore) does not mean that using it is wrong.

In fact, go to Uni and do Physics and it's all calculus and differentiation and integration (well most of it).
 
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watatank

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alcalder said:
Why not? Of course you can. Using the tools you have to hand to reach the right answer is never wrong. Just because they don't teach calculus or encourage it in physics (anymore) does not mean that using it is wrong.

In fact, go to Uni and do Physics and it's all calculus and differentiation and integration (well most of it).
Click to expand...
You're not wrong there. Just a few physics lectures at uni so far and its all calculus...

ALso, don't memorise the formulas like a sucker. They give them all to you in the exam anyway. But you do have to understand what they mean and is going on and how to apply it etc....
 
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watatank said:
You're not wrong there. Just a few physics lectures at uni so far and its all calculus...

ALso, don't memorise the formulas like a sucker. They give them all to you in the exam anyway. But you do have to understand what they mean and is going on and how to apply it etc....
Click to expand...

Yesss !!!! imma may wanna be a telecommunications engineer !
I'm sick and tired of remembering English quotes and Maths formulas.
 
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fwong

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xiao1985 said:
g force is easy... just find force applied and get that divide by mg and you have your g force...

question 2 and 3 are weird... you will need to assume that the thrust is momentary... then i suppose you have two ways to do the question:

u2 = v2 + 2as
and find the max height

v = u + at
find the time which it takes to max height and use
s = ut + 1/2 a t 2

4) answer 2 and 3 should be the same

5) is up to you...
Click to expand...
"Just find force ..." Which force? Gravity? Applied force? Net force? Or reaction force? A little knowledge is a dangerous thing!
 
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xiao1985

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fwong said:
"Just find force ..." Which force? Gravity? Applied force? Net force? Or reaction force? A little knowledge is a dangerous thing!
Click to expand...
apologies, resultant force (ie net force)
 
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