help !! (1 Viewer)

香港!

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Napoleon said:
your the beast =P not me, thanks for doing on
is it easy for you?
mind helping me with a few more?
Just post all the questions you need help w\...
I'm sure all those beasts and monsters out there will help you:p
 

KFunk

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When 0 < &theta; < 90&deg; then sin&theta; < tan&theta;

Hence &radic;(rgsin&theta; ) <&radic;(rgtan&theta; ), that is, it doesn't have enough speed so it will start to slip down to slope, hence friction will be up the slope.
 

KFunk

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For part ii)

&sum; vertical forces = 0 hence -------> Ncos&theta; + Fsin&theta; = mg (1)

&sum; horizontal forces = mv<sup>2</sup>/r -----> Nsin&theta; - Fcos&theta; = mv<sup>2</sup>/r (2)

sin&theta; x (1) - cos&theta; x (2) yeilds:

F(sin<sup>2</sup>&theta; + cos<sup>2</sup>&theta; ) = mgsin&theta; - mv<sup>2</sup>cos&theta;/r

subbing in the value of v

F = mgsin&theta; - mgsin&theta;cos&theta; = mgsin&theta;(1 - cos&theta; ) up the hill
 

Dumsum

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I pretty much had it until I read KFunk's post which proved me wrong (had wrong friction direction)

The trick though is in the line (1) x sin@ - (2) x cos@
 

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