Why two isotherms do not intercept each other.

Two lines of force in an electric field never intersect each other. Why?

If action and reaction are equal and opposite, why do they never cancel each other?

Maximum and minimum values of the resultant of two forces, acting at a point, are 15 N and 7N respectively. If the value of each force is increased by 1 N and these two new forces act at 90^@ to each other, what would be the value of the resultant ?

No two electric field lines can intersect each other. Why?

Given statements in (a) and (b). Identify the statements given below as contrapositive or converse of each other. (b) If a quadrilateral is a parallelogram, then its diagonals bisect each other. (i) If the diagonals of a quadrilateral do not bisect each other, then the quadrilateral is not a parallelogram. (ii) If the diagonals of a quadrilateral bisect each other, then it is a parallelogram.

Write self-reduction process with balanced chemical reaction in the extraction of copper from copper matte. Why is the process called 'self-reduction'?

Gravitational force is a conservative force, but frictional force is non-conservative Why ?

If two circles do not intersect or touch each other, then the maximum number of common tangents can be drawn is "_________"