Throwing a dart from a roof - Velocity

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Homework Help Overview

The problem involves a dart being thrown horizontally from a rooftop, with a specified time of flight and the angle at which it strikes the ground. The subject area pertains to kinematics and projectile motion.

Discussion Character

  • Exploratory, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the initial conditions of the dart's motion, particularly the initial vertical velocity being zero. There is an exploration of the final vertical velocity after 2 seconds and its relation to the horizontal component of velocity. The use of trigonometric relationships to connect the angle of impact with the velocities is also examined.

Discussion Status

Some participants have provided calculations and reasoning regarding the vertical and horizontal components of the dart's motion. There is acknowledgment of the correctness of the calculations presented, but no explicit consensus or final resolution has been reached.

Contextual Notes

The original poster indicates a lack of understanding of the problem and seeks guidance, while other participants build on the initial conditions and calculations without providing a complete solution.

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Homework Statement



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?

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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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?
 
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?

so

tan(53.1) = 19.6 / Vfx

Vfx = 14.7 m/s

Does that seem right?
 
Yes that looks correct.
 
Yay! thank you very much :)
 

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