Physics Quiz 4

The air layer between two shirts behaves like insulating media. Air in general is a good thermal insulator, but it can transmit heat through convection. However, if the air pockets inside the insulating material are separated from each other, heat flow from one air pocket to another cannot happen easily.

Our body supplies the heat, and the clothes help to trap body heat and keeps the heat from escaping into the air. This is what keeps us warm.

It was the Danish astronomer, Olaus Roemer, who, in 1676, first successfully measured the speed of light. His method was based on observations of the eclipses of the moons of Jupiter.

Shock-absorbers are usually made of steel as it has higher elasticity. They are used in vehicles so that the time interval of the jerk increases. Hence, the rate of momentum decreases. Therefore, during the jerk, a lesser force is exerted on the passengers.

A concave lens is used to correct short-sightedness (myopia). A short-sighted person's focus is focusing before the back of the eyeball. The concave lens pushes the rays of light further apart so that they arrive together in proper focus at the back of the eye.

Nuclear reactors operate on the principle of nuclear fission, the process in which a heavy atomic nucleus splits into two smaller fragments. The nuclear fragments are in very excited states and emit neutrons, other subatomic particles, and photons.

As per WHO The standard audible capacity of a healthy human being is in the range of 45-50 decibels. Humans can hear sounds between 0 and 180 decibels. To be precise, noise becomes harmful when it exceeds 75 decibels (dB) and is painful above 120 dB.

On the Moon, an astronaut cannot drink lemonade with the help of straw because there is no atmosphere on the Moon. There is no air on the moon and therefore, no air pressure to push the liquid up the straw.

When the medium is dense, the molecules in the medium are closely packed, which means that the sound travels faster. Therefore, the speed of sound increases as the density of the medium increases.

The velocity of sound in the air does not change with the change of Pressure of gas (air). The speed of sound increases with the increase of the temperature of the medium.