Question

can a scalar product of two vectors be negative? provide a proof and give an example ?​

Answer 1

Sure it can.

If a quantity is a product of two vectors, it is a scalar.

"Work done" is such an example. It is a product of force and displacement. And both are vectors, i.e., both specify magnitude as well as direction. But is is a scalar quantity.

MORE:-

Power = (Work done)/(Time)

But you can also write,

Power = (Force)(Velocity).

Since, W = Fs and v = s/t.