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1. The problem statement, all variables and given/known data

An object is to be thrown through a window 3.25 m high a distance 8 m away. It is launched at an angle 75 degree above the horizontal.

The initial launch speed at the specified angle which will allow the projectile to pass through the window is 13.3 m/s.

What is the final speed of the object (that is, the speed at which it flies through the window)?

Y= height

Yo= initial height

Voy= initial speed

Vf= final velocity

g= gravity

t= time

2. Relevant equations

1)Y= Yo+Voy*t-(1/2)gt^2

2)Vf= Vo+at

3. The attempt at a solution

By using the y= yo+Voy*t-(1/2)gt^2 formula,

= 3.25+ (13.3sin75)t-(1/2)(-9.81)t^2

I found the time t=2.85 s

But then the answer i got by using the formula Vf= Vo+at

= 13.3+ (-9.81)(2.85)

= -14.7 m/s

IS wrong!!What is my mistake??

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# Homework Help: Final velocity need help

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