Physics Quiz 3

Among the given materials sound travels fastest in steel. Sound travels fastest through solids. This is because molecules in a solid medium are much closer together than those in a liquid or gas, allowing sound waves to travel more quickly through it. Sound cannot travel in a vacuum as there is no medium.

When sunlight incident on raindrops formation of a Rainbow occurs in the sky. These raindrops work as a prism. When sunlight hits a raindrop, some of the light is reflected. The electromagnetic spectrum is made of light with many different wavelengths, and each is reflected at a different angle. Thus, spectrum is separated, producing a rainbow.

The melting point increases with an increase in pressure except for ice. The melting point of ice decreases when pressure increases. This strange behaviour of the ice is observed because water expands when it freezes i.e. ice occupies more volume than liquid water.

The sum of kinetic energy and potential energy is negative. This is because for the velocity less than escape velocity the missile is bounded due to the gravitational field of the earth. Hence its total energy is negative.

Water and petrol are immiscible with each other and petrol which forms the upper layer continues to burn. Water is heavier than petrol, petrol will come above the water and continue the contact with the atmosphere (oxygen).

When the two ice cubes are pressed together, melting point of ice is lowered, so they melt to form a thin layer of water (between them). On releasing the pressure, the water formed freezes because decrease in pressure raises the freezing point. Hence they unite to form one cube. When water freezes, water molecules form a crystalline structure maintained by hydrogen bonding.

Due to low air pressure, it is difficult to breathe at higher altitudes. The air at higher altitudes is colder, less dense, and contains fewer oxygen molecules.

The main attribute common to all lightning rods is that they are all made of conductive materials, such as copper and aluminium. Copper and its alloys are the most common materials used in lightning protection.

A colour-blind person cannot distinguish between certain colours. Colour blindness often happens when someone cannot distinguish between certain colours. This usually happens between greens and reds, and occasionally blues.

The modulus of rigidity, also known as shear modulus, is the ratio of shearing stress to shearing strain. It is the elastic coefficient when a shear force is applied resulting in lateral deformation.