$5.$ Calculate the tension required by the deltoid muscle to support a $3$ kg ball held in the hand as illustrated below.

Mass of arm $=3\mathrm{.}5$ kg

Centre of gravity of arm $($Xarm$)=35$ cm from shoulder joint.

Point of attachment of deltoid muscle to humerus $($Xd$)=15$ cm from shoulder joint.

Line$-$of$-$action of Deltoid muscle $=18$ degrees to humerous.

Distance from shoulder joint to centre of hand $($Xball$)=65$ cm

Assume that the gravitational acceleration g $=10$ m$/$s$2$