Is Earth losing gravity? According to some calculations, the Earth is losing 50,000 metric tons of mass every single year, even though an extra 40,000 metric tons of space dust converge onto the Earth’s gravity well, it’s still losing weight. Why is gravity only an attractive force? Why is gravity only an attractive force? Because […]
Can you get struck by lightning in the bathtub?
Can you get struck by lightning in the bathtub? Most people hit by lightning are outside. But, according to Snopes.com, lightning striking into the ground near homes has sent electricity up pipes and into sinks and bathtubs. However, incidents like this are uncommon because rarely is someone doing dishes or showering at the “precise moment […]
How can you reduce the intensity of sound?
How can you reduce the intensity of sound? Levels of sound pressure and levels of sound intensity decrease equally with the distance from the sound source. Sound power or sound power level has nothing (!) to do with the distance from the sound source. What is the best frequency for humans? 75M Hz Are 60 […]
What is the importance of metastable state?
What is the importance of metastable state? In a three-level laser, the material is first excited to a short-lived high-energy state that spontaneously drops to a somewhat lower-energy state with an unusually long lifetime, called a metastable state. The metastable state is important because it traps and holds the excitation energy, building up a… What […]
What are three scientific theories?
What are three scientific theories? Examples of scientific theories in different areas of science include: Astronomy: Big Bang Theory. Biology: Cell Theory; Theory of Evolution; Germ Theory of Disease. Chemistry: Atomic Theory; Kinetic Theory of Gases. Physics: General Relativity; Special Relativity; Theory of Relativity; Quantum Field Theory. What makes a bad scientific theory? Bad scientific […]
What happens if you add a second pulley to a pulley system?
What happens if you add a second pulley to a pulley system? The powerful mechanical advantage of a pulley is in using many pulleys at once. Combining multiple pulleys decreases the amount of force necessary to move an object by increasing the amount of rope used to raise the object. How does a single movable […]
Which is appropriate for a helicopter approaching an airport for landing?
Which is appropriate for a helicopter approaching an airport for landing? If not otherwise authorized or directed by the tower, pilots of fixed-wing aircraft approaching to land must circle the airport to the left. Pilots approaching to land in a helicopter must avoid the flow of fixed-wing traffic. What is the minimum ceiling requirement for […]
Which is the best example of heat being transferred mainly by radiation?
Which is the best example of heat being transferred mainly by radiation? Heat transfer by radiation occurs when microwaves, infrared radiation, visible light, or another form of electromagnetic radiation is emitted or absorbed. An obvious example is the warming of the Earth by the Sun. A less obvious example is thermal radiation from the human […]
Why does a spoon look bigger in a glass of water?
Why did the number of dark peppered moths increase after the 1850s?
Why did the number of dark peppered moths increase after the 1850s? The evolution of the peppered moth is an evolutionary instance of directional colour change in the moth population as a consequence of air pollution during the Industrial Revolution. Later, when pollution was reduced, the light-coloured form again predominated. Did moths used to be […]