JEE Main 2015 · 11 Apr · Shift 1 · Physics Q2

PhysicsSingle correct+4 / -1Question 2 of 90

A vector $\vec A$ is rotated by a small angle Δθ radians (Δθ<<1) to get a new vector $\vec B$ . In that case $|\vec B-\vec A|$ is :

|\vec A|\left(1-\dfrac{\Delta\theta^2}2\right)

|\vec A|\,\Delta\theta

|\vec B|\,\Delta\theta-|\vec A|

Answer and worked solution

Official answer: C

$|\vec B-\vec A|=2|\vec A|\sin\dfrac{\Delta\theta}2\approx|\vec A|\,\Delta\theta$ for small Δθ.

JEE Main 2015 · 11 Apr · Shift 1, Physics question 2