Laws of Motion -03- Moment Of A Force

Forces act as indicated on a rod AB which is pivoted at A. Find the anticlockwise moment of each force about the pivot.

Transcript

00:00Hi friends, when you wake up in the morning, always thank God for giving you another day

00:06to express your full potential and love.

00:10Moment of a force.

00:12That's what it is.

00:15Maybe this question can give you an idea related to the moment of a force.

00:21A thin stick is connected to an axis at one end.

00:25Several forces act on the stick.

00:26Now, we are asked to calculate the anticlockwise moment.

00:34When the moment of force acts on an object, the object will rotate about a certain axis.

00:40The rotation may be anticlockwise.

00:46Let's calculate the moment of force.

00:50Each force will have a different the line of action.

00:53So we will make a table containing all the forces acting on the stick.

00:58Next, we will determine the moment arm.

01:04The simple explanation is like this, that the moment arm is the length of the line from

01:07the axis that is perpendicular to the line of action of the force.

01:13We can draw the line of action of the force as a dotted line.

01:19The distance from the axis to the line of action of F1 is half the length of the stick.

01:24That is the moment arm of F1.

01:29For F2, draw the line of action of the force as before.

01:35That distance is a line perpendicular from the axis to the line of action of the force.

01:42Finally the length of that distance is L sine of 60 degrees, or half L root 3.

01:50Knowing this value we can calculate the moment of force.

01:55The moment of force is the multiplication of the force acting on an object by the moment arm.

02:02So the moment of force of F1 is half L F1.

02:06And the moment of force of F2 is half L F2 root 3.

02:13Based on the criteria of the question, the moment of force that rotates the stick counterclockwise

02:17will have a positive sign.

02:21It turns out that calculating the moment of force is not difficult.

02:25Happy learning everyone!