6 Everyday Facts That Are Scientifically Wrong

1. Objects float in water because they are lighter than water


Objects float in water not because they are lighter than water but because they are less dense than water. A less dense object has less mass per unit volume, which means a material less dense than water occupies more volume than water of the same weight.

When an object is placed in water, it displaces some water. The water then pushes the object up by an upward force (upthrust) that is equal to the weight of the displaced water.

For an object to float, the weight of the object must be less than or equal to the upthrust of the water on the object.

2. Wood floats and metal sinks

Anything less dense than water with float on water. Lithium, sodium and potassium are metals and they are less dense than water so they float on the surface of the water.

The shape of the metal also determines whether it will sink or not. For example, though iron is more dense than water, an iron box may float in water because it is full of air which is less dense.

3. Liquids rise in a straw because of a “suction force”.

Sipping a drink through a straw is something so simple that we usually take the science behind it for granted. Many people assume that sipping creates a suction force that pulls the liquid up.

But the reality is that the sipping action lowers the air pressure in your mouth, which allows the atmospheric pressure outside the straw to push the liquid up the straw.

Sipping through straw

4. Heat and Temperature are the same thing

Heat is a measurement of the transfer of thermal energy between the molecules of a substance. It is measured in Joules.

Temperature is a degree of hotness of a substance. It is measured in Celsius (°C), Kelvin(K), Fahrenheit (°F), or Rankine (R).


5. A meteor or spacecraft entering the atmosphere becomes hot due to friction with the atmosphere

When a meteor or spacecraft enters the atmosphere, the heat of entry is not primarily caused by friction. It is caused by adiabatic compression of air in front of the object.

Meteor

6. The sun is yellow

Even the Kryptonians sent their son to earth because it has a yellow sun. Well, it appears yellow but the Sun is actually white. The yellow colour you see is due to atmospheric scattering.

The sun produces light of different wavelengths which make up the different shades of blue, green and red. White light produced by the sun is a mixture of blue, green and red.

The atmosphere scatters light of shorter wavelength more than light of long wavelength. Blue light has a short wavelength, so it is easily scattered by the atmosphere. The sun then appears yellow as a result of the “missing” blue light.

White sun

In space there in no atmospheric scattering, so the sun is white when seen from space.

The “missing” blue light isn’t really missing at all, but is scattered throughout the atmosphere, making the sky appear blue.


Sydney Chako

Mathematics, Chemistry and Physics teacher at Sytech Learning Academy. From Junior Secondary School to Tertiary Level Engineering Mathematics and Engineering Science.

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