### Video Transcript

If the couples π sub one and π sub two are in equilibrium, where π sub one equals 50π, then find the value of π sub one minus π sub two equals what.

The key point in this statement is that π sub one and π sub two are in equilibrium. Physically, π sub one and π sub two are force pairs that potentially exert a torque on a body. The fact that π sub one and π sub two are in equilibrium means two things. First, it means they have equal magnitudes. And second, it means they are opposites of one another.

So when we say π sub one and π sub two are in equilibrium, we mean that they donβt exert a net force on the body, if any, on which they act. In other words, the body itself is also in equilibrium.

Using point number two and the fact that π sub one is equal to 50π, we know that π sub two must equal negative 50π. So π sub one minus π sub two must equal 50π minus minus 50π, or 100π. Thatβs the value of π sub one minus π sub two.