Category: Physics

At what elevation does it get harder to breathe? Oxygen levels are highest at sea level, but they fall steadily at increasing altitudes. Most men won’t notice any effect until about 5,000 feet; even at one mile above sea level, breathing is comfortable at rest but becomes labored with exertion. Can you breathe 30000 feet? […]

Will entropy ever stop increasing? Entropy is the loss of energy available to do work. Another form of the second law of thermodynamics states that the total entropy of a system either increases or remains constant; it never decreases. Entropy is zero in a reversible process; it increases in an irreversible process. Why is entropy […]

What is a soft shadow? Figure 3.20 Hard-edged shadows indicate light from a small point source. In many cases, using soft shadows (which are less distinct and fade off toward the edges, as in Figure 3.21) for some of your lights tends to look more realistic than using only hard shadows. How do shadows change […]

Is gold a main group element? Examples of main group elements include helium, lithium, boron, carbon, nitrogen, oxygen, fluorine, and neon. Elements that are not main group elements are the transition metals (such as titanium, copper, and gold), the lanthanides (such as lanthanum and erbium), and the actinides (such as actinium and plutonium). What are […]

What kind of energy is involved when ice melts? kinetic energy What happens to potential energy while the water is melting? When ice or any other solid melts, its potential energy increases. Indeed, this is the only increase in energy, since the thermal kinetic energy, or temperature, does not increase while melting. At each phase […]

How do you increase density of oil? What you can do is mix the oil with something else. A solution (two or more things mixed together) of oil plus another ingredient would increase the density of the oil. This is the same reason that salt water is heavier than fresh water, the weight of the […]

Why is C 14 not used to date dinosaur bones? But carbon-14 dating won’t work on dinosaur bones. The half-life of carbon-14 is only 5,730 years, so carbon-14 dating is only effective on samples that are less than 50,000 years old. To determine the ages of these specimens, scientists need an isotope with a very […]

What are 4 types of air masses? There are four categories for air masses: arctic, tropical, polar and equatorial. Arctic air masses form in the Arctic region and are very cold. Tropical air masses form in low-latitude areas and are moderately warm. Polar air masses take shape in high-latitude regions and are cold. What are […]

What does the name halogen mean? Group 7A (or VIIA) of the periodic table are the halogens: fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At). The name “halogen” means “salt former”, derived from the Greek words halo- (“salt”) and -gen (“formation”). Who are the members of halogen family? Halogen, any of the […]

Does TBI shorten your life? These changes may affect a person’s ability to function in their everyday life. Despite initial hospitalization and inpatient rehabilitation services, about 50% of people with TBI will experience further decline in their daily lives or die within 5 years of their injury. Do TBI patients sleep a lot? Conclusions: Sleepiness […]