MCQ
The angle between vectors $(\overrightarrow {\rm{A}} \times \overrightarrow {\rm{B}} )$ and $(\overrightarrow {\rm{B}} \times \overrightarrow {\rm{A}} )$ is
  • A
    Zero
  • $\pi$
  • C
    $\pi /4$
  • D
    $\pi /2$

Answer

Correct option: B.
$\pi$
b
(b)$\vec A \times \vec B$ and $\vec B \times \vec A$ are parallel and opposite to each other. So the angle will be $\pi$.

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Similar questions

The work done on a particle of mass $m$ by a force, $k\left[\frac{x}{\left(x^2+y^2\right)^{3 / 2}} \hat{i}+\frac{y}{\left(x^2+y^2\right)^{3 / 2}} \hat{j}\right]$ ( $K$ being a constant of appropriate dimensions), when the particle is taken from the point $(a, 0)$ to the point $(0, a )$ along a circular path of radius a about the origin in the $x$-y plane is :
If $\vec F$ is the force acting on a particle having position vector $\vec r$ and $\vec \tau$ be the torque of this force about the origin, then
A liquid column of height $0.04 \mathrm{~cm}$ balances excess pressure of soap bubble of certain radius. If density of liquid is $8 \times 10^3 \mathrm{~kg} \mathrm{~m}^{-3}$ and surface tension of soap solution is $0.28 \mathrm{Nm}^{-1}$, then diameter of the soap bubble is . . . . . . .. . $\mathrm{cm}$.

$\text { (if } g=10 \mathrm{~ms}^{-2} \text { ) }$

How many times is escape velocity $({V_e})$, of orbital velocity $({V_0})$ for a satellite revolving near earth
70 calories of heat are required to raise the temperature of 2 mole of an ideal gas at constant pressure from 30° C to 35° C. The amount of heat required to raise the temperature of the same gas through the same range at constant volume is:
  1. 30 calories.
  2. 50 calories.
  3. 70 calories.
  4. 90 calories.

A particle is moving in a circle with uniform speed. Its motion is
Two particles $A$ and $B$ start moving with velocities $20 \,m / s$ and $30 \sqrt{2} \,m / s$ along $x$-axis and at an angle $45^{\circ}$ with $x$-axis respectively in $x y$-plane from origin. The relative velocity of $B$ w.r.t. $A$ is ........... $m / s$
The linear velocity of a rotating body is given by $\overrightarrow v = \overrightarrow \omega \times \overrightarrow r ,$where $\overrightarrow \omega $ is the angular velocity and $\overrightarrow r $ is the radius vector. The angular velocity of a body is $\overrightarrow \omega = \hat i - 2\hat j + 2\hat k$ and the radius vector $\overrightarrow r = 4\hat j - 3\hat k,$ then $|\overrightarrow v |$ is
$100\  g$ of water is heated from $30^o\ C$ to $50^o\ C$ Ignoring the slight expansion of the water, the change in its internal energy is ...... $kJ$ (specific heat of water is $4184\  J/kg/K$)
A ball moving with a velocity of $6\, m/s$ strikes an identical stationary ball. After collision each ball moves at an angle of $30^o$ with the original line of motion. What are the speeds of the balls after the collision ?