Main characteristics of couple:
Sol.: The main characteristics of couple
1. The algebraic sum of the forces, having the couple, is zero.
2. The algebraic sum of moment of the forces, constituting couple, about any point is the same, and equal to the moment of couple itself.
3. A couple can't be balanced by a single force, but can be balanced only by a couple, however of opposite sense.
4. Any number of coplanar couples can be reduced to single couple, whose magnitude will be equal to algebraic sum of moments of all the couples.