Physics

Radium was formerly used in self-luminous paints for watches, nuclear panels, aircraft switches, clocks, and instrument dials. More than 100 former watch dial painters who used their lips to shape the paintbrush died from the radiation from the radium that had become stored in their bones. Soon afterward, the adverse effects of radioactivity became widely known. Radium was still used in dials as late as the 1950s. Although tritium's beta radiation is potentially dangerous if ingested, it has replaced radium in these applications.

The study of stars, galaxies, and the creation of the universe, including predictions about how it will proceed from here.

ION ENERGY CONSISTS OF ELECTRIC CHARGES CALLED PROTONS (+), NUTRONS (0) AND ELECTRONS (-) CHARGES.ITS PRESENT IN AN ATOMIC SHELL.CHARGES +- CANCEL EACH OTHER TO KEEP BALANCE....

In opposite direction, but they are designed to propel the boat forward even if they rotate in opposite directions.

A mirror is a reflective surface. Light passes through the glass and hits the silver backing, reflecting off of it. (The angle of incidence equals the angle of reflection.) A lens, on the other hand, does not reflect light; it refracts it. After entering the glass, light refracts differently depending on the shape of the lens and also creates a focal point where the refracting light comes to a point. This differs for different lenses -- convex or concave -- which is why there are different lenses for different types of eyeglasses.

There is a small attachment with a hole in it which acts as a whistle. It is inserted into the spout of the kettle and when the water starts to boil, the steam makes a sound as it escapes.

In electromagnetic waves -- or ocean waves, for that matter -- a crest is the peak, or maximum height, of the waveforms. A trough is the lowest point. The wavelength of a wave is measured from one crest (peak) to the next or from one trough to the next.

Strain aging could be described as " normal wear and tear " or the fatigue that is experienced under normal conditions, whereas Dynamic strain would be an out of the normal range stress condition like a one time over stress condition where the sum of much strain aging is experienced in one " dynamic" occurrence.

The land mass is heavier even tough the sea covers 2/3 of the earth's surface it still has land under the sea hence it is heavier...

Gas, as well as everything in the universe has density, though some densities are either too high or too low to be detected, observed or measured by the human eye nor the technological gadgetry designed and used by scientists for that specific purpose

The same it weighed when it was liquid---but it has a greater volume because ice is "fluffier" than water.

It's an ammeter. It's used to detect and measure electric current.

Centrifugal force is the force that is equal in magnitude but opposite in direction to the centripetal force, which is the force directed toward the center of a rotating or revolving mass.

Think of it this way. Let's say you have a yo-yo and let it unwind. Then you start swinging it around your head in a circle parallel to the ground. The force that keeps the yo-yo in its circular path is the centripetal force. Without it, the yo-yo would not continue in its circular path but would fly off in a straight line, which it is inclined to do. The tension in the string, the force that makes the string taut, is the centrifugal force.

statement that any particle of matter in the universe attracts any other with a force varying directly as the product of the masses and inversely as the square of the distance between them. In symbols, the magnitude of the attractive force F is equal to G (the gravitational constant, a number the size of which depends on the system of units used and which is a universal…

In electrolysis, oxygen and hydrogen gas are produced at different electrodes (oxygen at the anode and hydrogen at the cathode). Since these electrodes do not have to be in close proximity, the hydrogen and oxygen will bubble upwards into separate collection vessels.

If you needed to separate hydrogen and oxygen once mixed, the easiest way I can think of would be to cool the mixture to ~60K. At this point the oxygen would condense and leave hydrogen gas.

Molecules in a gas move constantly, freely, randomly, in all directions and at high speeds. They are able to do so because the intermolecular force of attraction between the molecules is negligible when in a gaseous state. This constant motion of the molecules causes them to collide with anything in their path. For example, dust particles will be bombarded by the molecules moving at high speeds, causing them to have a zigzag motion.

Brownian motion also takes place in molecules in a liquid, but to a less obvious extent than in a gas.

yes. A fly puts weight on a plane gosh!!!! It’s like asking does a normal person put weight on a bike!? But yes fly do put weight on a plane that is flying if it lands, but it doesn’t put a lot of weight on because they are so small. There is your answer...

Yes. For instance, the 2-dimensional vector (1,0) has length sqrt(1+0) = 1

A vector only has zero magnitude when all its components are 0.

Intermolecular forces (dipole-dipole, dispersion and hydrogen bonds). These forces are weaker than chemical (covalent) bonds. Therefore molecular solids are soft, and have a generally low melting temperature.

A chemical or physical change not requiring a change in the temperature of the substance, as in the formation of marten site.