Question

An experimental device imparts a force of magnitude f = 37 lb to the front edge of the rim at a to simulate the effect of a slam dunk. compute the moment of the force f about point o and about point

b. the moments are positive if counterclockwise, negative if clockwise. finally, locate a point c from the base at o to the location on the ground where the force imparts zero moment. the distance d from point o to point c is positive if c is to the right of o, and negative if to the left.

Answer 1

a) τ = -518 lb-inch , b) d = 0 inch

Step-by-step explanation:

a) The moment of a force is given by

τ = F x r

The bold letters indicate vectors, we can solve the magnitude of this expression with

τ = F r sin θ

and the angle by the right hand rule.

In general, the applied force is perpendicular to the rubber and in such a direction that the moment is opposite to the movement, therefore the angle is 270 = -90º and the sin 270 = -1

τ = -F r

To perform a complete calculation, the radius of the rubber is needed, for example for a small car the radius is about 14 inch = 1,167 feet

τ = -37 14

τ = -518 lb-inch

The point o is assumed to be the center of the wheel, the negative sign indicates that the moment is clockwise

b) As the rubber is a circle and the force is perpendicular, the vector product gives an emoticon perpendicular to the rubber, so that this value decreases to zero we must reduce the application point (distance), that is, the distance must be zero.

d = 0 inch