A force F → = α i ^ + 3 j ^ + 6 k ^ is acting at a point r → = 2 i ^ - 6 j ^ - 12 k ^ . The value of α for which angular momentum about origin is conserved is:

Step-by-step solution

If L → = constant then τ → = 0 So r → × F → = 0 ⇒ F → should be parallel to r → so coefficient should be in same ratio. So α 2 = 3 - 6 = 6 - 12 So α = - 1