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:

Given:

`vecr = 3hati - hatj  m, vecv = 3hatj + hatk  m"/"s, and m = 1  kg`

Angular momentum:

`vecL - vecr xx mvecv = (3hati - hatj) xx (3hatj + hatk)`

`vecL = (-hati - 3hatj + 9hatk)`

Magnitude:

`|vecL| = sqrt((-1)^2 + (-3)^2 + (9)^2) = 91`