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#### Infinitegrim

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Had physics last year and im trying to find the velocity of something...

Horizontally fired projectile fired 5 feet above the ground, it travels 290 feet from the point its fired before it hits the ground.

What is the time and initial velocity?

I will update with a picture.

#### Infinitegrim

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Knowns:

IGNORE AIR RESISTANCE

-acceleration due to gravity 9.8m/ss
-intial height 5ft
-final height 0ft.

Now to find time it would be the same as finding how long it took an object to fall from 5ft.

would time be .5577 seconds? if t= square root of (2H/g)

#### SirLagALot

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Well I don't have a calculator atm, but you're on the right track
Once you have the time needed to fall, you'll know the time it took to travel horizontally. Then just divide the horizontal distance by your time there, and you should get the initial velocity
Once I figure out how to convert from your inanely annoying units (
) I'll post up a worked solution

#### Schizms

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Quote:
 Originally Posted by SirLagALot Well I don't have a calculator atm, but you're on the right track Once you have the time needed to fall, you'll know the time it took to travel horizontally. Then just divide the horizontal distance by your time there, and you should get the initial velocity Once I figure out how to convert from your inanely annoying units ( ) I'll post up a worked solution
looks like all you need is to change accel... which is 32.2 ft/s^2

#### MrDeodorant

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d=(Vi)(t) + (1/2)(a)(t^2) = (1/2)(a)(t^2) from rest.
d / (1/2)(a) = (t^2)
5 / (1/2)(32.2) = (t^2)
t = 0.249 seconds

d = (Vi)(t)
Vi = d / t
Vi = 1164.659 feet per second.

You're on your own for significant figures, though.

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