Let us consider two vectors A and B.
As per the question, the two vectors are perpendicular to each other.
Hence the angle between them 
We are asked to calculate the resultant of these two vectors.
As per parallelogram law of vector addition, the resultant of two vectors are-

[cos90=0]

This is the way by which we can add two perpendicular vectors.
The type of energy that is produced by the system that is described is heat energy. The correct answer is D.
350kg because to get Newton’s it’s mass x Gravity, earths gravity is x10 so 3500 divided by 10 is 350