Question

The position vector of 1 kg object is `vecr = (3hati - hatj)` m and its velocity `vecv = (3hati + hatk)` ms^-1. The magnitude of its angular momentum is `sqrtx` Nm where x is ______.

Options

• 90

• 91

• 92

• 93

Answer 1

The position vector of 1 kg object is `vecr = (3hati - hatj)` m and its velocity `vecv = (3hati + hatk)` ms^-1. The magnitude of its angular momentum is `sqrtx` Nm where x is 91.

Explanation:

Angular momentum, `vecL = m(vecr xx vecv)`

= `1[(3hati - hatj) xx (3hatj + hatk)] = (9hatk - 3hatj - hati)` NS

`|vecL| = sqrt(9^2 + (-3)^2 + (-1)^2) = sqrt91` Ns