NTA JEE Main 31st August 2021 Shift 2 - Physics

Statement I: If three forces $$\vec{F}_1$$, $$\vec{F}_2$$ and $$\vec{F}_3$$ are represented by three sides of a triangle and $$\vec{F}_1 + \vec{F}_2 = -\vec{F}_3$$, then these three forces are concurrent forces and satisfy the condition for equilibrium.
Statement II: A triangle made up of three forces $$\vec{F}_1$$, $$\vec{F}_2$$ and $$\vec{F}_3$$ as its sides were taken in the same order, satisfies the condition for translatory equilibrium.
In the light of the above statements, choose the most appropriate answer from the options given below:

Statement-I: Two forces $$\vec{P} + \vec{Q}$$ and $$\vec{P} - \vec{Q}$$ where $$\vec{P} \perp \vec{Q}$$, when act at an angle $$\theta_1$$ each other, the magnitude of their resultant is $$\sqrt{3P^2 + Q^2}$$, when they act at an angle $$\theta_2$$, the magnitude of their resultant becomes $$\sqrt{2P^2 + Q^2}$$. This is possible only when $$\theta_1 < \theta_2$$.
Statement-II: In the situation given above. $$\theta_1 = 60°$$ and $$\theta_2 = 90°$$
In the light of the above statement, choose the most appropriate answer from the options given below :

If velocity $$V$$, time $$T$$ and force $$F$$ are chosen as the base quantities, the dimensions of the mass will be:

A block moving horizontally on a smooth surface with a speed of 40 m s$$^{-1}$$ splits into two parts with masses in the ratio of 1 : 2. If the smaller part moves at 60 m s$$^{-1}$$ in the same direction, then the fractional change in kinetic energy is:

A system consists of two identical spheres each of mass 1.5 kg and radius 50 cm at the ends of a light rod. The distance between the centres of the two spheres is 5 m. What will be the moment of inertia of the system about an axis perpendicular to the rod passing through its midpoint?

If $$R_E$$ be the radius of Earth, then the ratio between the acceleration due to gravity at a depth $$r$$ below and a height $$r$$ above the earth surface is: (Given: $$r \lt R_E$$)

Four identical hollow cylindrical columns of mild steel support a big structure of mass $$50 \times 10^3$$ kg. The inner and outer radii of each column are 50 cm and 100 cm respectively. Assuming uniform local distribution, calculate the compression strain of each column.
[use $$Y = 2.0 \times 10^{11}$$ Pa, $$g = 9.8$$ m s$$^{-2}$$]

Two thin metallic spherical shells of radii $$r_1$$ and $$r_2$$ ($$r_1 < r_2$$) are placed with their centres coinciding. A material of thermal conductivity $$K$$ is filled in the space between the shells. The inner shell is maintained at temperature $$\theta_1$$ and the outer shell at temperature $$\theta_2$$ ($$\theta_1 < \theta_2$$). The rate at which heat flows radially through the material is:

A mixture of hydrogen and oxygen has volume 500 cm$$^3$$, temperature 300 K, pressure 400 kPa and mass 0.76 g. The ratio of masses of oxygen to hydrogen will be:

A bob of mass $$m$$ suspended by a thread of length $$\ell$$ undergoes simple harmonic oscillations with time period $$T$$. If the bob is immersed in a liquid that has density $$\frac{1}{4}$$ times that of the bob and the length of the thread is increased by $$\frac{1}{3}$$rd of the original length, then the time period of the simple harmonic oscillations will be:

For a body executing S.H.M.:
(a) Potential energy is always equal to its K.E.
(b) Average potential and kinetic energy over any given time interval are always equal.
(c) Sum of the kinetic and potential energy at any point of time is constant.
(d) Average K.E. in one time period is equal to average potential energy in one time period.
Choose the most appropriate option from the options given below:

Choose the incorrect statement:
(a) The electric lines of force entering into a Gaussian surface provide negative flux.
(b) A charge $$q$$ is placed at the centre of a cube. The flux through all the faces will be the same.
(c) In a uniform electric field net flux through a closed Gaussian surface containing no net charge, is zero.
(d) When an electric field is parallel to a Gaussian surface, it provides a finite non-zero flux.
Choose the most appropriate answer from the options given below:

The equivalent resistance of the given circuit between the terminals $$A$$ and $$B$$ is:

A current of 1.5 A is flowing through a triangle, of side 9 cm each. The magnetic field at the centroid of the triangle is:
(Assume that the current is flowing in the clockwise direction.)

A coil is placed in a magnetic field $$\vec{B}$$ as shown below:

A current is induced in the coil because $$\vec{B}$$ is:

The magnetic field vector of an electromagnetic wave is given by $$B = B_0\frac{\hat{i}+\hat{j}}{\sqrt{2}}\cos kz - \omega t$$ where $$\hat{i}$$, $$\hat{j}$$ represents unit vector along x and y-axis respectively. At $$t = 0$$ s, two electric charges $$q_1$$ of $$4\pi$$ coulomb and $$q_2$$ of $$2\pi$$ coulomb located at $$\left(0, 0, \frac{\pi}{k}\right)$$ and $$\left(0, 0, \frac{3\pi}{k}\right)$$, respectively, have the same velocity of $$0.5c\hat{i}$$, (where $$c$$ is the velocity of light). The ratio of the force acting on charge $$q_1$$ to $$q_2$$ is:

Consider two separate ideal gases of electrons and protons having same number of particles. The temperature of both the gases are same. The ratio of the uncertainty in determining the position of an electron to that of a proton is proportional to:

A free electron of 2.6 eV energy collides with a H$$^+$$ ion. This results in the formation of a hydrogen atom in the first excited state and a photon is released. Find the frequency of the emitted photon. (h = $$6.6 \times 10^{-34}$$ J s)

If $$V_A$$ and $$V_B$$ are the input voltages (either 5 V or 0 V) and $$V_0$$ is the output voltage then the two gates represented in the following circuits A and B are:

Statement I: To get a steady DC output from the pulsating voltage received from a full wave rectifier we can connect a capacitor across the output parallel to the load $$R_L$$.
Statement II: To get a steady DC output from the pulsating voltage received from a full wave rectifier we can connect an inductor in series with $$R_L$$.
In the light of the above statements, choose the most appropriate answer from the options given below:

A particle is moving with constant acceleration $$a$$. Following graph shows $$v^2$$ versus $$x$$ (displacement) plot. The acceleration of the particle is _________ m s$$^{-2}$$.

A sample of gas with $$\gamma = 1.5$$ is taken through an adiabatic process in which the volume is compressed from 1200 cm$$^3$$ to 300 cm$$^3$$. If the initial pressure is 200 kPa. The absolute value of the workdone by the gas in the process = _________ J.

A parallel plate capacitor of capacitance 200$$\mu$$F is connected to a battery of 200 V. A dielectric slab of dielectric constant 2 is now inserted into the space between plates of capacitor while the battery remain connected. The change in the electrostatic energy in the capacitor will be _________ J.

A resistor dissipates 192 J of energy in 1 s when a current of 4 A is passed through it. Now, when the current is doubled, the amount of thermal energy dissipated in 5 s is _________ J.

A long solenoid with 1000 turns m$$^{-1}$$ has a core material with relative permeability 500 and volume $$10^3$$ cm$$^3$$. If the core material is replaced by another material having relative permeability of 750 with same volume maintaining same current of 0.75 A in the solenoid, the fractional change in the magnetic moment of the core would be approximately $$\frac{x}{499}$$. Find the value of $$x$$.

At very high frequencies, the effective impedance of the given circuit will be _________ $$\Omega$$.

Cross-section view of a prism is the equilateral triangle $$ABC$$ shown in the figure. The minimum deviation is observed using this prism when the angle of incidence is equal to the prism angle. The time taken by light to travel from P (midpoint of BC) to A is _________ $$\times 10^{-10}$$ s. (Given, speed of light in vacuum = $$3 \times 10^8$$ m s$$^{-1}$$ and $$\cos 30° = \frac{\sqrt{3}}{2}$$)

In a Young's double slit experiment, the slits are separated by 0.3 mm and the screen is 1.5 m away from the plane of slits. Distance between fourth bright fringes on both sides of central bright fringe is 2.4 cm. The frequency of light used is $$x \times 10^{14}$$ Hz.

A bandwidth of 6 MHz is available for A.M. transmission. If the maximum audio signal frequency used for modulating the carrier wave is not to exceed 6 kHz. The number of stations that can be broadcasted within this band simultaneously without interfering with each other will be _________.

The diameter of a spherical bob is measured using a vernier callipers. 9 divisions of the main scale, in the vernier callipers, are equal to 10 divisions of vernier scale. One main scale division is 1 mm. The main scale reading is 10 mm and 8th division of vernier scale was found to coincide exactly with one of the main scale division. If the given vernier callipers has positive zero error of 0.04 cm, then the radius of the bob is _________ $$\times 10^{-2}$$ cm.