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## Homework Statement

Standing on the ground 3.0 m from the wall of a building, you want to throw a package from your 1.6 m shoulder level to someone in a second-floor window 4.1 m above the ground

a)At what speed should you throw the package so it just barely reaches the window?

b) At what angle should you throw the package so it just barely reaches the window?

I know how to solve it conceptually but the workings are causing me problems mainly because I am asked to determine the 2 crucial unknowns.

## The Attempt at a Solution

Assuming the projectile crosses the window at the apex of the trajectory.

vyf = vyi -gt

0 = vyi -9.8t

t = vi sin Θ/g

y(vi sin Θ/g) = y(0) +vi.t - 0.5gt^2

y(vi sin Θ/g) - y(0) = (vi sin Θ)(vi sin Θ/g) - 4.9(vi sin Θ/g)^2

2.7 = [(vi ^2 sin^2Θ)/g] -4.9[(vi^2 sin^Θ)/g^2]

I cannot assume Θ= 45 because part b asked for the angle. However, without knowing the angle, I cannot determine the initial velocity-self-contradictory, if you ask me.