# Physics

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A skier is gliding along at 7.49 m/s on horizontal, frictionless snow. He suddenly starts down a 14.4° incline. His speed at the bottom is 28.5 m/s. What is the length of the incline?

• Physics -

figure the height first:
mgh=1/2 m(28.5^2-7.49^2)

then distance= h/sin14.4

• Physics -

why do we subtract the two velocities?

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I have this same question.. got it wrong

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are u at mac????....doing cappa questions???? .....i got the answer...its 1.55*10^2 m

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yes. but how did you get it because i have different numbers

• Physics -

do u have an extension number??? u can cal me 51185.
he has outline the equations above

mgh=1/2m(final velocity-initial velocity)

>therefore the m will cross out on both sides
>then we knw that accelaration= -9.8m/s2
>do the calculations on the left side ov the equation, divide by 9.8m/s2 n nt
-9.8m/s2 , because that will mean u r going to get a negative distance which can't exist. if my explanation doesnt make sense try callin ma extension to see if i can help.

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oh okay i got that ! thanks.
for the second part..how long it takes to reach the bottom.. do u use t = d/v?

• Physics -

you welcome.
for the second part use this equation

s=1/2(u+v)t

s= to the distance you got in the previous answer

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okay but what does 'u' refer to?

Also, for question #7, how did you figure out the total velocity for the entire trip?

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u= initial velocity.

omg question 7 was sooo stupid!!
all you do is get the distance from the house to the tree and divide by the (final time - initial time. ( we only consider the distance form the house to the tree because according to displacement when you run from lets say point p to point q and back to point p the your displacement is zero just like the case of the lampost)

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okay thanks ! was your velocity really small and negative then?

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nope it was positive :)

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alrighttyy. did u get number 13, 14 or 18?

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i got 255m but am sure we have different numbers in the question.