The A string on a cello vibrates in its first normal mode with a frequency of 220 Hz. The vibrating segment is 67.0 cm long and has a mass of 1.70 g. (a) Find the tension in the string.
N
(b) Determine the frequency of vibration when the string vibrates in three segments.
Hz

Glass is transparent to visibile light under normal conditions; however, at extremely high intensities, glass will absorb most of the light incident upon it. this works through a process known as multiphoton absorption. in this process, several photons are absorbed at the same time. if very intense light whose photons carry 2ev of energy is shined onto a material with a band gap of 4ev, that light can be absorbed through two-photon absorption, because two photons have the right amount of energy to bridge the band gap. what is the minimum number of photons of 800-nm light that are needed to equal or exceed the band gap of fused silica glass

Idon’t quite understand this problem

Find the dimensions and area of the largest rectangle that can be inscribed in the upper half of the ellipse. (give your answers in terms of a and b. enter the dimensions as a comma-separated list.)