A 14.5 kg mass, fastened to the end of a steel wire of unstretched 1.0 m, is whirled in a vertical circle with an angular velocity of 2 rev/s at the bottom of the circle. The cross- sectional area of the wire is `0.065" cm"^(2)`. Calculate the elongation of the wire when the mass is at the lowest point of its path.

Explanation

The cross - sectional area of each femurs
`a=10cm^(2)`
`therefore` Total cross -section area of two femurs
`A=2xx10cm^(2)`
`=2xx10^(4)m^(2)`
The mass of the upper part of a human body `m=40kg`
Acceleration of gravity `g=10ms^(-2)`
`therefore` The force acting on the upper part of a human body ,
F=mg
`=40xx10`
`thereforeF=400N` The force is acting vertically down
`therefore` Average pressure
`ltPgt=(F)/(A)=(400)/(20xx10^(-4))`
`=20xx10^(4)=2xx10^(5)Nm^(-2)`