Determine the minimum velocity needed to throw a rock to just clear the roof line of a 50m tall building from the ground level and a distance of 30m from the base of the buliding. Assume that the initial angle is 60 degrees.

Question

anonymous · Answer

This is the question from a test I already took, but I'd like to know the answer before I take the final, so if a similar question appears I will know what to do.

anonymous · Answer

the answer should be 32.68 m/s depending on how you round

anonymous · Answer

can you show your work or a picture of your work please?

anonymous · Answer

I shall in a couple minutes

anonymous · Answer

thank you

anonymous · Answer

anonymous · Answer

so I just realized that was wrong and forgot about the 60 degree thing

anonymous · Answer

use equations, 
$$L=\frac{v_0^2\sin{2\alpha}}{g}$$
and
$$h=\frac{v_0^2\sin{\alpha}^2}{2g}$$

anonymous · Answer

^

anonymous · Answer

is angle given?
is this problem exactly like this?

anonymous · Answer

sorry my answer also wrong

anonymous · Answer

you need two equations:
$$x=v_{ox}t=v_0\cos{\alpha}t$$
and
$$y=v_0\sin{\alpha}t-gt^2/2$$
take t from first, insert into second

anonymous · Answer

|dw:1386909057026:dw|