How to solve

Learning Goal:

To be able to calculate the moment of a force about a

specified axis.

When the moment of a force is computed about a point,

the moment and its axis are always perpendicular to the

plane that contains the force and the moment arm. In

some instances it is important to find the component of

this moment along a specified axis that passes through

the point.

In addition to scalar analysis, $M_a,$ the magnitude of the

moment of a force about a specified axis, can be found

using the triple scalar product

$M_a=u_a*(rF)=|[u_{a_x},u_{a_y},u_{a_z}],[r_x,r_y,r_z],[F_x,F_y,F_z]|$

where $u_a$ is the unit vector that describes the direction of

the specified axis and $r$ is the position vector to the point

where the force $F$ is applied.

Figure

$1$ of $1$

Part A

Unscrewing a bolt requires a moment of $50\mathrm{.}0lb*ft.$ The $z$ axis passes through the center of the bolt. A force

$F=\{-51\mathrm{.}7i+9\mathrm{.}00j+6\mathrm{.}00k\}lb$ is applied to the end of the wrench. $($Figure $1)$ What minimum length, $d,$ must

the wrench have to turn the bolt?

Express your answer numerically in inches to three significant figures.

View Available Hint$($s$)$

Previous Answers

Incorrect; Try Again; One attempt remaining

Part B Complete previous part$($s$)$

Part C Complete previous part$($s$)$

Provide Feedback