In general, why are men taller than women?

Height is determined by genetic and environmental factors. And some of the genes determining height, like the aromatase gene, are located on the Y chromosome, which is available only in the males. Therefore, the increased height. 

What is bone made of?

A typical bone has an outer layer of hard or compact bone, which is very strong, dense and tough. Inside this is a layer of spongy bone, which is like honeycomb, lighter and slightly flexible. In the middle of some bones is jelly-like bone marrow, where new cells are constantly being produced for the blood. Calcium is an important mineral that bone cells need to stay strong. 

How do pain killers work?

Your body is full of nerve endings in your skin and tissues. Some of these nerve endings can sense pain, like from a burn or a blow to a body part. When cells in your body are injured or damaged, they release a chemical called prostaglandin.

When you take a pain killer medicine, it keeps injured or damaged cells from making and releasing prostaglandin. When the cells don't release this chemical, it means that the brain won't get the pain message as quickly or clearly. So your pain goes away or becomes less severe for as long as the cells aren't releasing the chemical. The pain killers you take will either disrupt the signal heading from the injured area to the brain, or it will change the way your brain interprets that signal. 

What makes popcorn pop?

A popcorn kernel is actually a seed. At its center is a tiny plant embryo, a life form in its earliest phase. The embryo is surrounded by soft, starchy material that contains water. Surrounding the embryo is a hard shell. When the kernel is heated to about 400 degrees Fahrenheit, the water turns to steam. The pressure from the steam causes the kernel’s shell to explode and the starch to spill out.

Why is the black box on an airplane called so, when it is actually painted orange?

Black boxes which usually hold the clues to a plane's crash, are built strong enough to survive bomb blasts, violent impacts and intense fires.  The black box records voice and flight data. The cockpit voice recorder continuously collects data. They are actually orange in color and a very high quality heat resistant paint is used, so that they can be spotted easily even at dimly lit crash sites. They are always placed in the tail end of the flight.

The term 'black box' is generally used to describe a thing/process which is not well understood by most people, but which produces something useful or well known. The term black box is used for the data recorder on airplane, in this context for similar reaso: the crash is the mystery process recorded by the black box - once you open up the black box, the process can be understood.

Why do bulls charge at red cloth?

Bulls are colour blind, so it's not the colour that attracts them, it is the swirling motion of the cape that agitates them. Bullfighters always use a red cape, but it is probably so the crowd can see it better. The color red really has no effect on a bull.