Doppler Effect
Doppler Effect We have heard an ambulance siren and felt that the ambulance is getting closer. When the ambulance approaches, the sirens sound higher, and when they move away, the sirens sound lower. That is, when … more
Measurement
Eratosthenes’ Calculation of Earth’s Circumference
Eratosthenes’ Calculation of Earth’s Circumference The first person to measure the earth’s size was Eratosthenes, an ancient Greek scientist about 2,000 years ago. Eratosthenes lived in Alexandria, near the Nile River’s mouth by the Mediterranean coast, … more
Archimedes Buoyancy 2
Why is the submerged volume important to understand buoyancy? It is so famous that the 3rd-century Greek philosopher Archimedes shouted “Eureka!” and ran out of the bathhouse naked. （What did Archimedes find out? – Quotations from … more
Molecular Weight Calculator
If you click on the elements in order, the molecular weight that is summed by adding the atomic weight is displayed. For example, if you want to know the molecular weight of water (H2O), click H … more
Digital Sampling
Digital sampling All sounds in nature are analog signals. Analog information holds information from all consecutive times. Since it is not possible to record all the values at all times, usually only the values at regular … more
Distance and Displacement
Distance One of the most used concepts is ‘distance,’ which means the total distance actually moved. If you move in zigzag, the actual distance traveled can be quite long, even if the straight distance is short. … more