A rubber cord has a cross -sectional area `1 mm^(2)`and total unstretched length`10.0cm`. It is streched to `12.0 cm` and then released to project a missile of mass 5.0 g.Taking young's modulus Y for rubber as `5.0xx10^(8) N//m^(2)`.Calculate the velocity of projection .

Answer

A, B, C

Explanation

Equivalent force constant of rubber cord
`k=YA/l=((5.0xx18^(8))(1.0xx10^(-6)))/((0.1))=5.0xx10^(3)N//m`
Now,from conservation of mechanical energy,
elastic potential energy of cord=Kinetic energy of missile
:. `1/2 k (Deltal)^(2)=1/2mv^(2) rArr:.v=(sqrt(k/m))Deltal`
`=(sqrt((5.0xx10^(3))/(5*0xx10^(-3))))(12.0-10.0)xx10^(-2)=20m//s`