Buoyancy Experiment
The fluid in the beaker is water, and its density is assumed to be 1 g/mL. The volume of the object is assumed to be 100 mL. Buoyancy When we wear a life jacket, our bodies float on the water … more
Measurement
Archimedes Buoyancy 1
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 middle school science textbooks） … more
Principle of Speed Gun
Doppler effect Electromagnetic waves (or sound waves) come into contact with another object while traveling; part of the wave is absorbed or reflected. A moving ball likewise absorbs or reflects some of the incoming waves. If the ball were moving, … more
Michelson Interferometer
Michelson interferometer The Michelson interferometer was invented by the American physicist Michelson. Although it has a simple structure, it can measure very small distance differences, such as the size of an atomic nucleus. The Michelson interferometer consists of the following … more
Eratosthenes’ Calculation of Earth’s Circumference 2
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, in northern Egypt. He … more
How to use a multimeter
Multimeter A multimeter is a measuring device that combines various measurement functions such as voltage, current, and resistance. Multimeters are classified into analog and digital multimeters according to how they operate. Analog multimeters were used a lot in the past, … more
Structure of an ammeter
Ammeter The strength of the current in the electrical circuit is measured using an ammeter. There is a rotor with a coil wound inside the ammeter. When the current flows through the ammeter, the coil and the rotor will have … more
Gulliver’s Nutrition
Why did the King of Lilliput serve 1728 meals to Gulliver? This is because the volume of two objects that resemble each other in three dimensions is proportional to the cube of length. Since Gulliver’s height is about 12 times … more
Spring Scales
A spring scale is a tool that measures the mass and gravity of an object using the spring’s elastic force. The spring of this scale is lengthened by gravity and shortened by elasticity. You can find out the gravity (or … more
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 an ambulance approaches with … more
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, in northern Egypt. He … 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 middle school science textbooks） … more