Wednesday

October 7, 2015
Posted by **Bala** on Tuesday, October 5, 2010 at 7:46pm.

- Physics -
**bobpursley**, Tuesday, October 5, 2010 at 7:47pmfigure the height first:

mgh=1/2 m(28.5^2-7.49^2)

then distance= h/sin14.4

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**Bala**, Tuesday, October 5, 2010 at 7:51pmwhy do we subtract the two velocities?

- Physics -
**Emily**, Tuesday, October 5, 2010 at 7:59pmI have this same question.. got it wrong

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**Bala**, Tuesday, October 5, 2010 at 8:01pmare u at mac????....doing cappa questions???? .....i got the answer...its 1.55*10^2 m

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**Emily**, Tuesday, October 5, 2010 at 8:02pmyes. but how did you get it because i have different numbers

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**Bala**, Tuesday, October 5, 2010 at 8:12pmdo 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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**Emily**, Tuesday, October 5, 2010 at 8:17pmoh okay i got that ! thanks.

for the second part..how long it takes to reach the bottom.. do u use t = d/v?

- Physics -
**Bala**, Tuesday, October 5, 2010 at 8:27pmyou 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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**Emily**, Tuesday, October 5, 2010 at 8:32pmokay 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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**Bala**, Tuesday, October 5, 2010 at 8:41pmu= 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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**Emily**, Tuesday, October 5, 2010 at 8:47pmokay thanks ! was your velocity really small and negative then?

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**Bala**, Tuesday, October 5, 2010 at 8:53pmnope it was positive :)

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**Emily**, Tuesday, October 5, 2010 at 9:04pmalrighttyy. did u get number 13, 14 or 18?

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**Bala**, Tuesday, October 5, 2010 at 9:17pmi got 255m but am sure we have different numbers in the question.