Using a precise digital kitchen scale and a smartphone with a pressure sensor, we can easily measure the change in weight and atmospheric pressure in different locations.
Flat-Earthers claim that an object falls down because it is denser than the air surrounding it. However, simple measurements show that things weigh less at a higher altitude where the air is less dense, contrary to the expectation if their claim is true.
Continue reading “Weight and Air Density Experiment”
Archimedes’ principle states that the upward buoyant force exerted on a body immersed in a fluid is equal to the weight of the fluid that the body displaces. Today we usually use B = -ρgV to calculate the buoyant force, where ρ is the fluid’s density, g is the gravitational acceleration, and V is the volume of the displaced fluid.
Archimedes discovered buoyancy earlier than Newton discovered gravity, and flat-Earthers dispute the presence of g in the buoyancy formula. In reality, buoyancy depends on the weight of the fluid, and the distinction between weight and mass only occurred after Newton. Archimedes’ principle still applies, only that we now have a better understanding of what weight is.
Continue reading “Gravitational Acceleration in Archimedes’ Formula”
The weight of an object is the force exerted on the object by gravity. The gravitational force exerted by the Earth on an object is what we feel as the ‘weight’ of the object.
Many flat-Earthers fail to understand that the gravitational force is just another name for ‘weight’. Much misinformation in flat Earth communities arises from this misunderstanding.
Continue reading “What We Feel as “Weight” is the Force of Gravity”
An egg will generally sink in freshwater, but if we pour salt into the water and stir it, then the egg will start to float. The reason is that after salt is added, the density of water increases. However, the relationship between density and if the egg floats or sinks is not a direct causality.
Flat-Earthers claim that the phenomenon “proves” things fall because of density, and that gravity does not exist. In reality, the density of the water determines the magnitude of buoyancy the egg receives. If the buoyancy is higher than the weight of the egg, the egg will float, and vice versa.
Continue reading “Egg and Salt Water”
Measurement can be direct measurement, like measuring length using a measuring tape; or indirect measurement, which is measuring something by measuring another.
Flat-Earthers love to discredit results of measurement which they deem ‘impossible’ or not supporting their beliefs; for example the distance to the Sun, the distance to stars, Sun’s temperature, the orbital and rotational velocity of the Earth, etc. Their usual excuse is that such measurements were not done directly, but indirectly. In reality, most measurement instruments we use every day do their measurements indirectly.
Continue reading “Direct and Indirect Measurements”
Buoyancy is an upward force exerted by a fluid (liquid or gas) that opposes the weight of an immersed object. Buoyancy happens because the fluid has a pressure gradient. Pressure gradient occurs because the fluid is affected by acceleration, such as the Earth’s gravitational acceleration.
Flat-Earthers makes buoyancy as an “explanations” on how things fall. They are wrong. Without Earth’s gravitational acceleration, buoyancy will not occur.
Continue reading “Buoyancy”