A string has its 4th harmonic at 31.5 Hz. What is the
frequency of its 3rd harmonic?
(Unit = Hz)

wavelength divides in half and speed stays the same.

the order for strong to weak forces such as

strong nuclear force → electromegnetic force → weak nuclear force → gravitational force

the fundamental forces are those forces that act between to objects or element to make interactions. there are four types of fundamental forces such as strong and weak nuclear forces (due to protons and electrons), electromagnetic force (due to the motion of electrons) and gravitational force (due to orbital movement of the planet). if these forces are arranged on the basis of their maximum strength then the order is

strong nuclear force → electromegnetic force → weak nuclear force → gravitational force

if the person is shown to have +90n, then ans is -10n.

if the person is shown to have -90n, then ans is +10n.

it was given as a lesson and guide for prayer.