Last Question of Exam 2?

[b^3]

since he runs directly there and doesnt swim at all, isnt k negligible? :S

Not exaclty, for the direct route to be faster, k has to be a certain value, other wise part running and part swimming is faster. But now I'm trying to think how I got the value of T with K still in it then.....?

[bobby1470]

since he runs directly there and doesnt swim at all, isnt k negligible? :S

Not exaclty, for the direct route to be faster, k has to be a certain value, other wise part running and part swimming is faster. But now I'm trying to think how I got the value of T with K still in it then.....?

exept the question says he runs directly to the resovoir or whatever it was :S

[b^3]

since he runs directly there and doesnt swim at all, isnt k negligible? :S

Not exaclty, for the direct route to be faster, k has to be a certain value, other wise part running and part swimming is faster. But now I'm trying to think how I got the value of T with K still in it then.....?

exept the question says he runs directly to the resovoir or whatever it was :S

Yes but that is waht I'm saying, for the direct route to be the best option, K has to be greater than "enter value here". I srsly don't know where my other equation with K came from, I know that I dropped the Swimming part of the time off? Oh well.

[4231]

yeh so the x value is root 7 on two. So you sub that into DT/dx=0 to solve for k. Then u get 5 root 37/74 or something like that. This is .4 or something and because it had to be a minimum time, and the previous question had a lower k value and gave a a larger time, i ended up saying k had to be greater than or equal to 5 root 37/74, since it said "values of k" and not value

[bobby1470]

iono i subbed root7/2 into T and the time taken to swim equalled 0 so i just said k>0 since it had to be positive

[b^3]

yeh so the x value is root 7 on two. So you sub that into DT/dx=0 to solve for k. Then u get 5 root 37/74 or something like that. This is .4 or something and because it had to be a minimum time, and the previous question had a lower k value and gave a a larger time, i ended up saying k had to be greater than or equal to 5 root 37/74, since it said "values of k" and not value

Dam my answer is right but my reasoning I think is wrong, how many marks was it worth? Am I going to lose a mark for incorrect reasoning (provided they can read the words I have written in that last question).

[Asx4Life]

yeh so the x value is root 7 on two. So you sub that into DT/dx=0 to solve for k. Then u get 5 root 37/74 or something like that. This is .4 or something and because it had to be a minimum time, and the previous question had a lower k value and gave a a larger time, i ended up saying k had to be greater than or equal to 5 root 37/74, since it said "values of k" and not value

Even if it said values, doesn't the minimum time only occur when k=a number?

[acinod]

iono i subbed root7/2 into T and the time taken to swim equalled 0 so i just said k>0 since it had to be positive

Exact same answer. Im interested to see how many people actually get fullmarks for this part. The smartest people at my school I talked to all had different answers :O

[bobby1470]

iono i subbed root7/2 into T and the time taken to swim equalled 0 so i just said k>0 since it had to be positive

Exact same answer. Im interested to see how many people actually get fullmarks for this part. The smartest people at my school I talked to all had different answers :O

\

LOLLL if we get it right then everyone else will fail
but seems like the chances are against us

[luken93]

I spent quite a while graphing this.

I got the minimum being 5root(37)/74

However, as k increases, x = 0 is the MAXIMUM, and from 0 -> infinity the value of T decreased, hence because he couldn't go beyond the root(7)/2, it was always the least time for 0 < x < root(7)/2

Hence k >=  5root(37)/74.....shame I didn't do >= not > XD

[BoredSatan]

lol i completely forgot k was positive..

and i got k<0.. GG

hopefully get 1 mark for some good reasons and working

[fitzm11]

yeh i also got the k is greater than or equal to root thing, was the second last one 1/4?

[BubbleWrapMan]

yeh i also got the k is greater than or equal to root thing, was the second last one 1/4?

I got 1/4

[fitzm11]

yeh i also got the k is greater than or equal to root thing, was the second last one 1/4?

I got 1/4

oh gooddd i hope you're one of those smart people everyone always relies on

[BoredSatan]

yeh i also got the k is greater than or equal to root thing, was the second last one 1/4?

I got 1/4

yep i got 1/4
and i think im smart..