Thread: A problem that can't be solved

1. A problem that can't be solved

Could somebody help me with these please

1- A pilot glided over a tower, located in a direct line with the runway, with 30 m to spare and touched down on the runway at a point 6500 m from the base from the tower, how high is the tower?

2- Using these formulas :
V= IR
R= (pL)/A
A= 3.14 $(0.5d)^2$

find the difference in current (I) that a copper wire (p=1.27* $10^-8$ * m) can carry over an aluminum wire (p= 2.7* $10^-8$ * m) with equal diameters (d) of .5 cm and a length (L) of 10 000 m carrying 110 V .

$10^-8$ is 10 to the power -8, couldn't type it right.

2. Originally Posted by Apathetic
Could somebody help me with these please

1- A pilot glided over a tower, located in a direct line with the runway, with 30 m to spare and touched down on the runway at a point 6500 m from the base from the tower, how high is the tower?
the anlgle with the horizontal at which the plane is descending should be given......

3. no, nothing given
a couple of hours left, still couldn't figure it out

the answer is 620 m according to the back of the book.

4. So there is 30 m of air space between the top of the tower and the plane when it flies over it? I tried a few 30 60 90 triangles to see if I could figure this out for you, but I'm not getting anything near the book answer.
The tower and the runway make a 90 degree angle, forming the two legs of your right triangle. I assume that since the tower will probably be less than 6500 m, I made the angle by the plane my 60 degree angle and the angle of elevation, where the plane lands my 30 deg. angle.

I called the tower height + the extra 30m, "x" and so my equation says:
tan 60 = 6500m/30m(x)
Solve for x I got x = 677, then subtracted the 30m of air space and got 647m for the tower

That is probably the way you should try to solve it, but it isnt the right answer. Hope that helps anyway. Good luck

5. Hey Molly, thanks a lot. You really helped me a lot.
how about the second one, I think it's so easy but my mind is totaly blocked out at this moment.
got about half an hour, will I be lucky?