GCSE Science Questions?

Question

1.

http://img140.imageshack.us/my.php?image=seismicoq5.gif


The answer to the question in that link is apparently (D) - could anyone give me some justification for that answer? Or is it actually wrong?


2. Why is this statement incorrect:

In a sunny country near the equator only a few solar cells are needed to replace a power station



3.

http://img262.imageshack.us/my.php?image=seismicspeedxk0.gif

If time = distance/speed and according to the graph, the distance is 6370 km to the earth's centre, then this must be doubled to 'travel down to the earth's core AND BACK'.

So time = (6370 x 2)/10, in my opinion, but that isn't an option. So what is the right answer and how?

Answer 1

1. I thought the answer was B, that only the S waves would travel to R since the P waves cannot travel through the outer core and R looked to be a little to the right of the wave tracing the path of the last P and S trajectory.

2. I'd imagine it's incorrect because at the equator the increased sunlight that would allow for good solar generation also creates the need for a lot of air conditioning which boosts electricity demands.

3. I have no idea how to answer that last question based on the information and answers provided. I'd be with you on your estimate of 1274 s.