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Projectile Motion Question

Is this problem solvable?

The question was something along the lines of:
A ball is launched at an angle of 30 degrees and lands on top of a building. It's landing point is 5m above the launch position. The distance between the launch position and building is 20m. Find the initial velocity.

[url=http://i5.minus.com/jI0W9cTyfchXJ.png]Diagram[/url]

In any kinematic equation involving acceleration (gravity) and displacement (5m), there are two variables. Is there some sort of way to substitute/eliminate?

The only way it seems to work is if the landing point is the max height, where the vertical velocity is equal to zero. The time and then the initial vertical velocity can be found with this information, and then finally the initial velocity. But the horizontal velocity that results from these values does not give a horizontal displacement of 20m.

October 24, 2014

2 Comments • Newest first

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Typically when you are not given time, the problem suggests using an energy balance method. If it made it 5 meters above whatever then it had to have had a certain initial kinetic energy. If you copy and pasted the whole problem I might be able to solve it.

Reply October 24, 2014
sidho

The Only way I can see this working is if you use 2 different x and y components.

Reply October 24, 2014