Physics

Keeping in view that; the distance between node and adjacent antinode is 30 cm. The wavelength is 60cm. A node is a point on a standing wave where the amplitude is minimum while antinode is the point of maximum displacement.

In transverse waves, particle of the medium vibrate in a direction perpendicular to the direction of wave motion.

Water in pipes freeze in cold countries. Due to the anomalous expansion of water, it expands instead of contacting when there is a fall in temperature below 4°c. So, the water pipes burst due to the excess space consumed by the ice after freezing.

According to Archimedes principle and we can note that the amount of water displaced by a needle is lesser than the amount of water moved out by the needle (that is displacement of the needle). So the needle initially stays on the surface of the water and then sinks into the water. Surface tension is a contractive tendency of the surface of a liquid that allows it to resist an external force. It is revealed, for example, in the floating of some objects on the surface of water, even though they are denser than water, and in the ability of some insects (e.g. water striders) to run on the water surface. This property is caused by cohesion of similar molecules, and is responsible for many of the behaviors of liquids.

The density of steel usually ranges between 7.75 and 8.05 g/cm3 and the density of mercury is 13.534 g/cm3. Mercury is denser than steel this will mean that the buoyant force is large enough to float the steel ball. Different materials usually have different densities, so density is an important concept regarding buoyancy, purity and packaging. Osmium and iridium are the densest known elements at standard conditions for temperature and pressure but not the densest materials. Less dense fluids float on more dense fluids if they do not mix.