Another Mechanics Query (1 Viewer)

[bleakarcher]

i think we are on the same side here lol. i havent realised

 

[hscishard]

This confusion motivates me to stop procrastinating, and finally get some study in this holidays

 

[bleakarcher]

i dont think u have the idea actually. u seem to think that say when a particle is dropped from a height h and reaches a distance h units from the origin its velocity is 0.
this is wrong. in resisted motion, it is referred to as final velocity. Final velocity is the velocity of the particle during the instanteous point in time it hits the ground ie the velocity of the particle just b4 it strikes 0.

 

[khfreakau]

wrong, u take the starting position as the origin alwayz

lol no.

and hscishard - my teacher said this of mechanics: "the forces bit is 4u - once you get to the actual motion bits and stuff, most mechanics questions become hard 3u level questions"

So yes, I can see why you would think it can be done by 3u methods. Also, it annoys me how in many questions it's never specified whether the resistance is an acceleration or a force. Even them, there's a question in patel which says it's a force when it's actually an acceleration >_>

 

[bleakarcher]

when is it you dont? i alwayz do and get the desired result, unless it is specified

 

[Drongoski]

lol no.

and hscishard - my teacher said this of mechanics: "the forces bit is 4u - once you get to the actual motion bits and stuff, most mechanics questions become hard 3u level questions"

So yes, I can see why you would think it can be done by 3u methods. Also, it annoys me how in many questions it's never specified whether the resistance is an acceleration or a force. Even them, there's a question in patel which says it's a force when it's actually an acceleration >_>

In maths, certain terms have assumed a well-established meaning; e.g. in a typical algebra question, "find x" does not mean you go round with a magnifying glass looking for the letter "x". Similarly "resistance" has a well-known meaning. It is, like friction, an opposing force - this has the effect of reducing the prevailing force being resisted, thereby slowing it down. This resisting force equivalently contributes a negative acceleration (deceleration) to the object. But no - resistance is a force - this force contributes a negative acceleration. So Patel is correct.

 

[bleakarcher]

drongoski
integral[sin^(-1)x/[1+x^2]] dx from x=-1 to 1
herez the link
http://www.angelfire.com/ab7/fourunit/cranbrook2006.pdf

 

[Drongoski]

drongoski
integral[sin^(-1)x/[1+x^2]] dx from x=-1 to 1
herez the link
http://www.angelfire.com/ab7/fourunit/cranbrook2006.pdf

Sorry can't do it - too hard.

Answer: zero

 

[Trebla]

integral[sin^(-1)x/[1+x^2]] dx from x=-1 to 1

The answer is zero, as the integrand is an odd function...

 

[bleakarcher]

ahh ok.
i havent learnt much about using the properties of even and odd functions in integrate

 

[Trebla]

If you want a more formalised proof:

 

[Drongoski]

Over the interval (1,-1) sin^-1 x is an odd function while 1 + x² is an even function. Therefore, their quotient:

is an odd function.

 

[Bobbo1]

If you want a more formalised proof:

This is so beautiful!!! (and not being sarcastic)
Once you get used to the other you forget the actual theory, lol

 

[failwhale]

yeah u do when v=0 x=0 because it hasn't fallen height, h, as of yet.

 

[hscishard]

i dont think u have the idea actually. u seem to think that say when a particle is dropped from a height h and reaches a distance h units from the origin its velocity is 0.
this is wrong. in resisted motion, it is referred to as final velocity. Final velocity is the velocity of the particle during the instanteous point in time it hits the ground ie the velocity of the particle just b4 it strikes 0.

You're correct, but I never said that it is 0. I said it wouldn't be 0. It's just that arj1 saying when x=h, v=0 confused me a bit

Forces aye... boy mechanics is going to be fun!

 

[Hermes1]

You're correct, but I never said that it is 0. I said it wouldn't be 0. It's just that arj1 saying when x=h, v=0 confused me a bit

Forces aye... boy mechanics is going to be fun!

lol i cant believe this thread is still going. and hscishard trust me mechanics is the best topic in 4 unit by far.