In the standing waves experiment, the string has a mass of 31.2 g and a length of 0.7 m. the string is connected to a mechanical wave generator that produce standing waves with frequency of f. the other end of the string is connected to a mass holder (mholder = 50.0 g) that carries a weight of 5.00x10^2 g. calculate the linear density of the string.

Auniform electric field exists in the region between two oppositely charged plane parallel plates separated by a distance of 1.60 cm . a proton is released from rest at the surface of the positively charged plate and strikes the surface of the opposite plate in a time interval of 3.20×10-6 s. 1-find the magnitude of the electric field. use 1.60×10-19c for the magnitude of the charge on an electron and 1.67×10-27kg for the mass of a proton 2-find the speed of the proton when it strikes the negatively charged plate