The first one, directly proportional to the length that the spring is stretched.
sandpaper and gravel surface
[I researched for you, since I am not in that particular level to know that knowledge yet. I assure this is accurate info :)]
The answer is A, red.
"Remember, the color you see is light REFLECTING off the surface of that object. If all colors are absorbed in to the surface EXCEPT red, red must be reflected, and you'll see red." - Yahoo User @Chap
Power of a lens is measured by f/D ratio where f is the focal length and D is the diameter of the lens (or mirror). The ratio gives you the power of an optical device or the light gathering power. Please remember a lens focuses the light. Imagine it as a light funnel. A lens works similar to a funnel. It bends the light rays and bring them to a concentrated spot or the focus, just like a funnel that gathers a liquid and bring it out through a narrow spout. Bigger the diameter of the funnel more liquid it can handle. Same way larger diameter of the lens more light it can bring to focal point. That is how you get f/D ratio.
I hope this makes it somewhat clear?
V = (1 / p) × p0×V0 = (1 / 219kPa) × 117kPa × 3L = 1.06L
