Question

Find the vector product (a X b) of the two given vectors: a = 2i + 3j + 4k, b = 3i + 5j. Here, i, j & k are unit vectors along three mutually perpendicular axes.

(a) -20i + 12j + k

(b) 10i + 6j + 1/2k

(c) 20i – 12j – k

(d) 10i – 6j -1/2k

I have been asked this question in homework.

I need to ask this question from Vector Product of Two Vectors in portion System of Particles and Rotational Motion of Physics – Class 11

Answer 1

The correct answer is (a) -20i + 12j + k

To elaborate: The cross product of a & b = i(0-20) – j(0 – 12) + k(10 – 9)

= -20i + 12j + k.

Note that this is not the same as b X a.