Young's Modulus

Introduction:

Young's modulus is a measure of how difficult it is to compress a material, such as steel. It measures pressure and is typically computed in terms of pascals (Pa). It is most commonly used by physicists to determine strain, a measurement of how a material, responds to a pressure, such as being squeezed or stretched.

Steel in Young's Modulus:

Understanding that steel is extremely hard to compress is important in everyday life. For example, it can be used to construct buildings and not become compressed, ruining the integrity of the building structure. A cube of steel that is only 1 meter (3.28 ft) in width, height, and depth, would only compress about one micron

while supporting the weight of one school bus, because of the amount of pressure it can withstand. In comparison, a cube that is comprised of the same dimensions and is made of lead has a lower value for Young's modulus. The lead cube would compress 14 times more than the steel cube.

Powerful Alloys

Titanium Alloys

Titanium (Ti) is a lightweight metal which forms amazing alloys with aluminium, vanadium, tantalum, niobium etc. These alloys are hard while being light. Initially, they were used in aerospace and aviation for making aircraft bodies. But now more applications are being found in automobile and general engineering. For example, the Tata Chemicals factory at Mithapur (India) uses huge Ti-alloy vessels for processing caustic soda (sodium hydroxide), which will otherwise corrode stainless steels in seconds.


Ti-alloys are difficult to weld and cut, hence they have not edged out steels. But they rule the roost in bio-medical implants. Ti alloys are now common in making jewellery, golf-clubs, expensive watches... there's a lot that can be done!

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Hooke's Law

The Trampoline

Hooke's law deals with springs and equilibrium. A trampoline is essentially an elastic disc that is connected to several springs. As you land on the trampoline the springs and the trampoline surface stretches as a result of the force of your body landing on it. 
Hooke's law states that the springs will work to return to equilibrium. In other words, the springs will pull back against the weight of your body as you land. The magnitude of this force is equal to that which you exert on the trampoline when you land. Hooke's law is stated in the following equation: F = -kx where F is force, k is the spring constant and x is the displacement of the spring. Hooke's law is merely another form of potential energy. Just as the trampoline is about to propel you up, your kinetic energy is 0 but your potential energy is maximized, even though you are at a minimum height. This is because your potential energy is related to the spring constant and Hooke's Law.

Intro of Density

Different densities of fluids.

Density is something that affects many of our everyday decisions. Consciously or not, we make mental calculations of density every time we interact with the physical world around us. Can we slide that box? Can we lift that rock? 

People are often confused about the difference between weight and density. There is an old riddle which highlights this confusion: “What weighs more – a pound of feathers or a pound of lead?” The answer, of course, is that both weight same – one pound. However, feathers are much less dense than lead, and therefore take up much more space. Density is the ratio of an object’s mass to its volume. This means that to find density, you must measure an object’s mass and divide it by the amount of space it takes up. The standard units of density are [kg/m3], although other units are commonly used such as [g/ml], [g/cm3], or [kg/l]. 1 ml has the same volume as 1 cm3.