When do we say two vectors are orthogonal?

When do we say that work is done?

Two vectors are equal if.

When is the sum of two vectors maximum and when minimum.

When do we call a body rigid?

When.do we say that a floating body is in stable equilibrium?

If veca and vecb are two vectors such that |veca+vecb|=|veca| then prove that vector 2veca + vecb is perpendicular to vector vecb .

The magnitudes, of the two vectors A and B are both not equal to zero but barA.barB=0Then the angle between the vectors is (in degrees).

.The sum and difference of two vectors are perpendicular to each other. Prove that the vectors are equal in magnitude.

State parallelogram law of vector addition and derive an expression for the resutlant of two vectors vecto P and vecto Q inclined to each other at angle theta .