Question

30. The X and Y components of vector A have
numerical values 6 and 6 respectively and that of
(A + B) have numerical values 10 and 9. What is
the numerical value of B?
(1) 2
(2) 3
(3) 4
(4) 5​

Answer 1

Answer:

Option (4) 5

Explanation:

[Bold letters like A, B signifies vectors]

[ i, j are the unit vectors along X and Y respectively]

According to the question,

A = 6i + 6j

A + B = 10i + 9j

So, B = (10i + 9j) - A

         = (10i + 9j) - (6i + 6j)

         = 4i + 3j

So, Numerical value of B = $\sqrt{4^{2} +3^{2} }$ = $\sqrt{16+9}$ = $\sqrt{25}$ = 5 (Answer)