Mechanics 1 P42 2014; Discussion!

[wizteddy13]

Dude. The period between 0-8 and the period between 8-27 have different accelerations, of course they're gonna have different values.

Yes, that's perfectly right. So, let me just ask this. If you were to consider the bounds as 8s and 0s, instead of 27 and 8 (just hypothetically saying), what time's distance are you calculating? Can you tell me the answer to that?

 

[wizteddy13]

You don't seem to understand how to apply the limits of integration. Why would you use t=27 as the upper limit? The body only moves according to the variable acceleration formula after t=8s, so when considering variable acceleration the t=0 point was at 8s. The body moved in variable acceleration for 19s only, and so the limits were 19 and 0. Or more simply put, integrate the expression and substitute t=19.

Brother! Finally I get a matching logic

 

[thementor]

Haha, let's just calm down for a second now.
The first part is perfectly fine, for first 8 seconds, distance is 8m

BUT, if we consider the equation, it only became active after reaching A, which was reached after T=8. So, what distance are you removing when you consider for s(8)?
If we put in the values, we get 9.6 m, as you showed. But, as you ALSO showed, the first 8 seconds was 8 m, NOT 9.6m.
SO what exactly did u remove when u subtracted s(8)

I feel sad for you. Or maybe for me. I dont know.

 

[A star]

Yes, that's perfectly right. So, let me just ask this. If you were to consider the bounds as 8s and 0s, instead of 27 and 8 (just hypothetically saying), what time's distance are you calculating? Can you tell me the answer to that?

you aare perfectly all correct in tis but bro T is the distance AFTER LEAVING A not in VAIABLE ACCELERATION open your eyes

 

[wizteddy13]

I feel sad for you. Or maybe for me. I dont know.

Ah, the cruelty of M1 exams...*sigh*

 

[A star]

Ah, the cruelty of M1 exams...*sigh*

well who so ever wins that one mark congratz to him i am gona study physics that is serously tough :O

 

[wizteddy13]

you aare perfectly all correct in tis but bro T is the distance AFTER LEAVING A not in VAIABLE ACCELERATION open your eyes

T is the total time the particle traveled, considering both the variable and non-variable regions. They said, it reached A at T=8. And then find distance from T=0 to T=27. So T is the time for the entire motion of the particle.

 

[Oishee Asif]

*sips coffee*
This is a civil war on my thread.
Sigh.

 

[wizteddy13]

well who so ever wins that one mark congratz to him i am gona study physics that is serously tough :O

Good point, I really should get back to Physics now...

 

[wizteddy13]

*sips coffee*
This is a civil war on my thread.
Sigh.

Hey, at least it's a civilized civil war?
*ba dum tss*

 

[thementor]

Hey, at least it's a civilized civil war?
*ba dum tss*

No not civilized. I have seen real wars that are civilized.

 

[wizteddy13]

No not civilized. I have seen real wars that are civilized.

So...you are saying we are acting uncivilized? Aww....:/

 

[17194]

Everyone seems to be having trouble with a simple concept. If I remember correctly the expression for s was s= 3/10 T^5/3. Now according to your logic you had to use the limits 8 and 27, as at 8s the body had already covered 8m. Well then substitute the value of t=8s in this expression. You should end up with 8m, if you are correct. But in reality, you get s=9.6

 

[thementor]

So...you are saying we are acting uncivilized? Aww....:/

No no! I am saying, that CAMBRIDGE makes you uncivilized. It makes your life a misery.

 

[wizteddy13]

Everyone seems to be having trouble with a simple concept. If I remember correctly the expression for s was s= 3/10 T^5/3. Now according to your logic you had to use the limits 8 and 27, as at 8s the body had already covered 8m. Well then substitute the value of t=8s in this expression. You should end up with 8m, if you are correct. But in reality, you get s=9.6

YES EXACTLY what I asked as well! If I get a satisfactory answer to that, I'll be satisfied.

Anyway, off to revise Physics now....Good luck to y'all

 

[wizteddy13]

No no! I am saying, that CAMBRIDGE makes you uncivilized. It makes your life a misery.

I see your point bro. True that.
However, I know for a fact that the Cambridge system is better than the national system we have, so I guess I'm kinda grateful for what I have

 

[thementor]

I see your point bro. True that.
However, I know for a fact that the Cambridge system is better than the national system we have, so I guess I'm kinda grateful for what I have

Meh, true! Still, they have a knack for giving candidates an MI during the exam. FYI, the term MI means myocardial infarction.

 

[Oishee Asif]

Meh, true! Still, they have a knack for giving candidates an MI during the exam. FYI, the term MI means myocardial infarction.

We know what a heart attack stands for. (Y)

 

[wizteddy13]

Meh, true! Still, they have a knack for giving candidates an MI during the exam. FYI, the term MI means myocardial infarction.

Hahah, true. Or, more likely, a cerebral infarction, when we can't even think straight

 

[Oishee Asif]

See?
SEE?