1.

The frequency v of the stretched string may depend on (i) the length of the vibrating segment 1 (ii) the tension in the stringand (iii) the mass per unit length m. Show that v prop 1/l sqrt(F/m).

Answer»

Solution :Tension is a force and its dimensions are `MLT^(-2)`
Dimensions of mass PER unit length are `ML^(-1)`
According to the given DATA `v prop l^(x)F^(y)m^(z)`
`v=kl^(x)F^(y)m^(z)`. K is a constnat WITHOUT any dimension.
Taking dimensions of terms on both sides
`T^(-1)=L^(x)(MLT^(-2))^(y)(ML^(-1))^(z)=L^(x)M^(y)T^(-2y)M^(z)L^((-z)`
`M^(0)L^(0)T^(-1)=L^(x+y-z)M^(y+z)T^(-2y)`
Equating the dimensions of T on both sides
`-1=-2y,y=1/2`
Equating the dimensions of M
`z+y=0, z=-y=(-1)/2`
Equating the dimensions of L
`0=xy-z+x+1/2+1/2, x=-1`
`v=kl^(-1)F^(1//2)m^(-1//2),v=1/lsqrt(F/m)`


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