# Breathing easy

What’s happening?

As you’re sitting quietly, reading Science by Email, it’s unlikely that you’ll be taking in deeps breaths. While your breathing is influenced by a range of factors, the average person will inhale and exhale anywhere between 12 and 20 times per minute, and will come nowhere near filling their lungs completely. Continue reading Breathing easy

# Drawing resistance

What’s happening?

Your veins have a rather nifty way of stopping blood from flowing back the wrong way – small flaps called ‘valves’ maintain a direction of blood-flow through your body. Some electronics also need to ensure the current only ever flows in a single direction. To do this, they use a component called a diode that acts a bit like an electrical valve. Continue reading Drawing resistance

# Tumbling probability

What’s happening?

Combination locks like these ones require a code with a string of digits that look something like ’3 – 16 – 7’. To unlock, the dial needs to be turned clockwise all the way around at least twice until the dial is pointing straight up (at the ‘twelve o’clock’ position). This ensures the tumblers are lined up correctly.
The first turn takes the dial from the starting position to point at number 2. It pushes the back tumbler so its gap (our black line) lines up with a release mechanism, or the latch. The second turn goes back the other way – anticlockwise – five places. This pushes the middle tumbler so its gap lines up as well. The third turn goes clockwise again by four places, rotating the front tumbler so all three gaps are together. This forms a space for the release mechanism to lift into, allowing you to lift the latch and open the lock. Continue reading Tumbling probability

# Spin cycle

What’s happening?

Before Isaac Newton, nobody gave too much thought to what made us fall back to Earth after we jump, or why we can’t float into the sky. This 17th century English philosopher had an interesting thought – he wondered if it had something to do with the reason planets stayed in orbits around the Sun. He came up with some rules about gravity and forces, explaining how all things moved. Continue reading Spin cycle

# Solar tea

#### What’s happening?

If you were to take all of the stuff that makes up our solar system, 99.86 per cent of it would be from the Sun, and consist of mostly hydrogen and helium. It’s not only a big object (109 planet Earths sitting side-by-side could fit across its diameter), its mass gives it a lot of gravity to squeeze all of that hydrogen and helium together.
All of that squeezing makes the Sun’s particles bump into one another rather energetically. In fact, the particles are pushed together so tightly, the forces that help hydrogen atoms stick together can reach out to one another and grab onto other atoms, making even bigger atoms. This is called nuclear fusion and is how hydrogen can turn into the slightly bigger element, helium. Continue reading Solar tea

# Lava fizz

#### What’s happening?

Water and oil aren’t exactly the best of friends. Because of their shape and the way their atoms stick together, they prefer keeping to themselves rather than mixing with one another. The Greek root for water is ‘hydro’, so we say that water is ‘hydrophilic’ (loves water) while oil is ‘hydrophobic’ (afraid of water). Because a drop of water has more mass than the same sized drop of oil, gravity pulls on it with more force, pulling it to the bottom. Continue reading Lava fizz

# Jellyfish tentacles

#### What’s happening?

You are watching fluid dynamics in motion. Fluid dynamics is the science of moving fluids. A fluid is something that flows and takes the shape of its container. Liquids like water, shampoo and volcanic lava are fluids. Even gases are fluids, although we can’t always see them flowing about. Continue reading Jellyfish tentacles