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Throwing a dart from a roof - Velocity

by mybrohshi5
Tags: dart, roof, throwing, velocity
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May8-10, 05:43 PM
P: 365
1. The problem statement, all variables and given/known data

A dart is thrown horizontally from a buildings rooftop. The dart's time of flight is 2.0 s. The dart sticks in the ground such that it makes a 53.1 degree angle with the ground.

With what speed was the dart thrown?

3. The attempt at a solution

I am studying for my final and i do not get this problem from one of my previous tests.

The answer is 14.7 m/s and i have no idea how to get it. Can anyone point me in the right direction.

Thank you :)
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May8-10, 06:10 PM
HW Helper
P: 6,202
Well if it is throw horizontally, then the initial vertical velocity is zero right? Using an equation of motion, what would be final vertical velocity when t=2?
May8-10, 06:36 PM
P: 365
Is the final vertical velocity when t=2 just 19.6 m/s

I got that from

Vf = Vi + at

oh so then from that the x component of the Vf will be the same as the velocity initial correct?


tan(53.1) = 19.6 / Vfx

Vfx = 14.7 m/s

Does that seem right?

May8-10, 06:44 PM
HW Helper
P: 6,202
Throwing a dart from a roof - Velocity

Yes that looks correct.
May8-10, 06:48 PM
P: 365
Yay! thank you very much :)

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