# Q. Two vectors $\vec{A}$ and $\vec{B}$ have equal magnitudes. The magnitude of $(\vec{A} + \vec{B})$ is 'n' times the magnitude of $(\vec{A} - \vec{B})$ . The angle between $\vec{A}$ and $\vec{B}$ is :

JEE Main JEE Main 2019

Solution:

## $\left|\vec{A} + \vec{B}\right| = 2a \cos\theta /2$ .....(1) $\left|\vec{A} -\vec{B}\right| = 2 a \cos \frac{\left(\pi-\theta\right)}{2} = 2a \sin\theta/2$ ......(2) $\Rightarrow n\left(2a \cos \frac{\theta}{2}\right)=2a \frac{\sin\theta}{2}$ $\Rightarrow \tan \frac{\theta}{2} =n$

You must select option to get answer and solution

## 1. The increase in pressure required to decrease the 200 L volume of a liquid by 0.004% (in kPa) is (Bulk modulus of the liquid ==2100 MPa)

Maharashtra CET 2006 Mechanical Properties Of Solids

## 2. Two discs of same moment of inertia rotating about their regular axis passing through centre and perpendicular to the plane of disc with angular velocities $\omega_1$ and $\omega_2$ . They are brought into contact face to face coinciding the axis of rotation. The expression for loss of energy during this process is:-

NEET 2017 System Of Particles And Rotational Motion

## 3. The period of revolution of planet A around the sun is 8 times that of B. The distance of A from the sun is how many times greater than that of B from the sun?

AIPMT 1997 Gravitation

## 4. To draw maximum current from a combination of cells, how should the cells be grouped?

AFMC 2006 Current Electricity

AFMC 2010 Atoms

## 6. The diameter of a flywheel is increased by 1%. Increase in its moment of inertia about the central axis is

JIPMER 2015 System Of Particles And Rotational Motion

## 7. The temperature of 100 g of water is to be raised from 24°C to 90°C by adding steam to it. The mass of the steam required for this purpose is

JIPMER 2015 Thermal Properties Of Matter

## 8. The spectrum of an oil flame is an example for ...........

KCET 2010 Dual Nature Of Radiation And Matter

## 9. A body of mass 4 kg is accelerated upon by a constant force, travels a distance of 5 m in the first second and a distance of 2 m in the third second. The force acting on the body is

KCET 2008 Laws Of Motion

## 10. Two equal forces are acting at a point with an angle of 60$^{\circ}$ between them. If the resultant force is equal to $40\sqrt{3}$, the magnitude of each force is

KEAM 2008 Laws Of Motion