Question

when are two or more force added to determine the resultant force and where are two or more forces subtracted to get the resultant force​

Answer 1

Explaination :

When are two or more force added to determine the resultant force?

Lets take an example of a box to understand -

A force which is applied by person A towards left side at the box which is 175N. And a force which is applied by person B from the same direction of person A which is 125.  

Then at that point when the two forces are applied at the same direction we will add to determine the resultant force.

Here in this the resultant force applied towards left side by person A and B will be 175 + 125 = 300N is the resultant force.

Where are two or more forces subtracted to get the resultant force​?

Now second point, let understand it by another example -

A force which is applied by person A towards left side at the box which is 175N. And a force which is applied by person B is opposit to the force applied by person A is 125N.

Here in this point both person A and B are applying forces towards their opposit direction. So here we will subtract to get the resultant force.

So, we will take the force which is greater (which is 175N). Hence, it will be 175 - 125 = 50N towards left side will be the resultant force.