20 N north because He is pushing it 20 newtons north.
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.
Answer:
answer is 10km
Explanation:
use "S =Ut "
S=distance U=velocity t =time
no need to convert time into seconds as the velocity has given in meters per minute
Answer:
The liquid gains thermal energy. The particles of liquid move faster. The space between the liquid particles increases. The liquid changes to a gas