Chapter $4$ Force System Resultants

GW $-$

$4-66.$ The Rollerball skate is an in$-$line tandem skate that uses two large spherical wheels on each skate, rather than traditional wafer$-$shape wheels. During skating the two forces acting on the ball of one skate consist of a $78-$lb normal force and a $13-$lb friction force. Determine the moment of both of these forces about the axle $AB.$

Problem $4-66$