Health & Science

What is the percentage of water is in your bones?

The human body is more than 60 percent water. Blood is 92 percent water, the brain and muscles are 75 percent water, and bones are about 22 percent water. A human can survive for a month or more without eating food, but only a week or so without drinking water.

How strong is a strand of human hair?

A single strand could hold 100g (3oz) in weight: the combined hair of a whole head could support 12 tons or the weight of two elephants. Weight for weight, it is not as strong as steel: more like aluminium, or reinforced glass fibres or Kevlar, which is used to make bulletproof vests.

Why is it dangerous to wake a sleepwalker?

It is a myth that it is dangerous to wake up a sleepwalker because it may cause them a heart attack, shock, brain damage, or something else. It is not a myth that it is dangerous to wake up a sleepwalker because of the possible injury the sleepwalker may inflict upon themselves or the person waking them up.

How much does the temperature change with altitude?

Although the actual atmospheric lapse rate varies, under normal atmospheric conditions the average atmospheric lapse rate results in a temperature decrease of 6.4C°/km (3.5F°/1,000 ft) of altitude above ground level. The measurable lapse rate is affected by the moisture content of the air (humidity).

How long does it take to get a sunburn?

Sunburn can occur in less than 15 minutes, and in seconds when exposed to non-shielded welding arcs or other sources of intense ultraviolet light. Nevertheless, the inflicted harm is often not immediately obvious. After the exposure, skin may turn red in as little as 30 minutes but most often takes 2 to 6 hours.

How can you keep from crying while cutting onions?

Cutting onions irritates the lachrymal glands, causing them to excrete tears. Chewing gum while cutting onions prevents tears by forcing you to breathe through your mouth. This disperses the irritant so that a significantly smaller amount reaches the lachrymal glands, preventing them from being irritated enough to release tears.

What happens to your body when you sneeze?

When you sneeze, air and particles travel through the nostrils at speeds over100 mph.  During this time, all bodily functions stop, including your heart, contributing to the impossibility of keeping one’s eyes open during a sneeze.