The moment (Physics) is the measurement of the tendency of a body to rotate. It is a different method than a translation of a specific body.
In most cases, the body starts moving in the direction of a force in a straight or curved line. But the moment is the force that tends the body to rotate about a fixed axis. It is also termed torque and represented by τ. Torque is actually a turning effect created by a force attached to a fixed point. If your body has no fixed point, then it will not rotate. In turn, there will be no moment of force produced in the body.
The process to calculate the moment is not complicated. You can easily check its problems if you have enough knowledge about its components. MeraCalculator offers a calculator that will help you calculate moments in no time.
Let’s discuss how you can find moments of force in Physics using its components.
Table of Contents
Components of Moment of Force:
The moment of force is a vector quantity because it also involves direction that we will discuss in the next sections. It is directly proportional to the force applied and the distance from a fixed point.
The moment arm is the distance of the pivot point to the point of application of force. It is also named as lever arm in some of the problems.
It is actually the perpendicular distance between these two points. You should have to do all calculations in the SI unit or any other same system of units.
For example, if you calculate the distance in meters (m) and Force in Newton (N), then the moment will be in the units of Newton-meter (Nm).
The change in units will also affect the value and calculation of the quantity. So, you will have to focus on this and solve the problems in a single system of units.
The direction of Moment:
As we have discussed moment is a vector because it has a specific direction. The direction of the body may either be clockwise or anti-clockwise to the pivot point (fixed point).
A student can get the direction using the right-hand rule.
“To use the right-hand rule in torque problems, take your right hand and point it in the direction of the position vector (r or d), then turn your fingers in the direction of the force and your thumb will point toward the direction of the torque.” (Quoted by Pasco.com)
Use a cross product calculator to find the cross-product of two vectors using the right-hand rule.
Here the position vector is the moment arm that we have discussed in detail in the above section. With this method, you can easily assume in which direction your body will rotate.
It is very helpful when you are dealing with numerical or daily life problems. We hope that you have a clear concept about this topic with our explanation. Now, we are going to deal with how you can calculate the moment of force quickly with simple steps.
How to find the moment of force in Physics?
You can calculate magnitude manually on paper or by getting a specific tool from the internet. In simple problems, you do not have to get a calculator for that. However, the moment calculator by CalculatorSchool could be very handy if you interest in using online tools.
You can do it after picking a pen and paper. But if you have complex problems with this task, you can get aid from a pre-programmed moment calculator.
For Magnitude only
To get the magnitude of the moment,
Moment = Force (F) x Moment arm (d).
You only have to put your given values in the above formula and you will get the answer. A student will not have to do anything else but multiple both the terms.
For example:
If we apply a force of 15N on a body at a distance of 20m from the pivot point, calculate the moment of force produced in the body?
Solution:
We know that a moment is a multiplication of force and moment arm as shown above. Then,
Moment = Force x Moment Arm
= 15 x 20 Nm
= 300 Nm
You can also do it using an online calculator. The only thing you have to do is paste your values there instead of paper.
It is an efficient way when you have to submit an online assignment where you have to add a screenshot of working steps.
For Magnitude and Direction:
The formula has given in the above section. For direction, we will simplify it and get an angle component to show and solve the direction problems.
Moment = Force (F) x Moment Arm (d)
For direction, Moment = F.d Sin θ
Here “θ” is the angle between F and d. It will also give you an idea about the direction of the moment of force to some extent.
For Example:
What will be the moment of force in a body on which 100N force applies at an angle of 30˚? The distance between the fixed point and application of Force is 44m.
Solution:
Moment = F. d Sin θ
= (100). (44) Sin (30)
= 4400 (0.5)
= 2200 Nm
For Example:
It is the total moment of force and. What will be the size of the moment of force if the system balance?
Solution:
As we know, the total force will be equal to the sum of all the applied forces in the balanced system. So,
By rearranging the above equations, we get,
40 – (20 + 40) N
40 – 60 N
-20 N
The negative sign with the size of the required force shows that the system may have a direction in the anti-clockwise direction. Hope you have learned the basic concept of the calculating moment with and without using online tools.
