Question

<hw 4: scalar moments
multiple choice question 4.6.
part a
determine the moment of force f₁ about point a on the beam.
m1 = 100 ft - lb ↺
m1 = 100 ft - lb ↻
m1 = 1600 ft - lb ↺
m1 = 1600 ft - lb ↻

Explanation:

Step1: Recall moment formula

The moment of a force $M$ about a point is given by $M = F\times d$, where $F$ is the force and $d$ is the perpendicular - distance from the point to the line of action of the force.

Step2: Identify force and distance for $F_1$

For force $F_1 = 400$ lb and the perpendicular distance from point $A$ to the line of action of $F_1$, $d = 4$ ft.

Step3: Calculate the moment

$M_1=F_1\times d=400\times4 = 1600$ ft - lb. The direction of the moment of $F_1$ about point $A$ is counter - clockwise (using the right - hand rule). In engineering notation, counter - clockwise moments are considered positive.

Answer:

M1 = 1600 ft - lb ⤶