Lakhmir Singh

The solubility of metal halides depends on their nature, lattice enthalpy and hydration enthalpy of the individual ions. Amongst fluorides of alkali metals, the lowest solubility of LiF in water is due to (i) Ionic nature of lithium fluoride (ii) High lattice enthalpy (iii) High hydration enthalpy for lithium-ion. (iv) Low ionisation enthalpy of the lithium atom

Answer: Option ii) Lattice and hydration enthalpies encourage the dissolving of alkali metal halides in water. Fluorides are soluble in this order: LiF, NaF, KF, RbF, CsF. The high lattice energy of...

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The reducing power of a metal depends on various factors. Suggest the factor which makes Li, the strongest reducing agent in aqueous solution. (i) Sublimation enthalpy (ii) Ionisation enthalpy (iii) Hydration enthalpy (iv) Electron-gain enthalpy

Answer: option iii) Li's hydration enthalpy is likewise high (highly exothermic). Li atom has the highest hydration enthalpy, making it the strongest reducing agent in aqueous media. - Li atom's...

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Assertion (A): Beryllium carbonate is kept in the atmosphere of carbon dioxide. Reason (R): Beryllium carbonate is unstable and decomposes to give beryllium oxide and carbon dioxide. (i) Both A and R are correct and R is the correct explanation of A. (ii) Both A and R are correct but R is not the correct explanation of A. (iii) Both A and R are not correct. (iv) A is not correct but R is correct.

Answer: Option (i) is correct. Beryllium carbonate is stable and decomposes to give beryllium oxide and carbon dioxide. The concentration of carbon dioxide grows in the right side, causing the...

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A uniform disc of radius R, is resting on a table on its rim. The coefficient of friction between disc and table is μ. Now the disc is pulled with a force F as shown in the figure. What is the maximum value of F for which the disc rolls without slipping?

Solution: Let the linear and angular acceleration be $a$ and $\alpha$ respectively. So, $F – f = Ma$ Where, M = mass of the disc f = force of friction applied at the centre Torque to disc,...

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Two cylindrical hollow drums of radii R and 2R and of a common height h, are rotating with angular velocities ω (anti-clockwise) and ω (clockwise) respectively. Their axes, fixed are parallel and in a horizontal plane separated by (3R + δ). They are now brought in contact (\delta \rightarrow 0)
a) show the frictional forces just after contact
b) identify forces and torques external to the system just after contact

a) We know, $v_{1} = \omega R$ $v_{2}=\omega^{2}R$ The direction of $v_{1}$ and $v_{2}$ are tangentially upwards in the figure, and they meet at point C. As a result, $f_{12}=-f_{21}$ represents the...

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A disc of radius R is rotating with an angular speed \omega_{o} about a horizontal axis. It is placed on a horizontal table. The coefficient of kinetic friction is \mu_{k}.
a) what happens to the linear speed of the centre of mass when the disc is placed in contact with the table?
b) which force is responsible for the effects in previous questions?

a) The linear velocity of the revolving disc changes as it is brought into contact with the table. b) Frictional force is responsible. The figure depicts it:

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Two discs of moments of inertia I_{1} and I_{2} about their respective axes and rotating with angular speed \omega_{1} and \omega_{2} are brought into contact face to face with their axes of rotation coincident.
a) calculate the loss in kinetic energy of the system in the process
b) account for this loss

a) Final kinetic energy = rotational + translation energy $K_{f}=KE_{R}+KE_{T}$ $\Delta \mathrm{K}=-I_{1} l_{2} / 2\left(I_{1}+l_{2}\right)\left(\omega_{1}-\omega_{2}\right) 2<0$ b) Because...

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The vector sum of a system of non-collinear forces acting on a rigid body is given to be non-zero. If the vector sum of all the torques due to the system of forces about a certain point is found to be zero, does this mean that it is necessarily zero about any arbitrary point?

The torques' vector total equals zero. However, the net force is not zero. The following is the mathematical explanation: $G_{i} \sum_{i=1}^{n} F_{t} \neq 0$ $\tau=\tau_{1}+\tau_{2}+\ldots...

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The centre of gravity of a body on the earth coincides with its centre of mass for a ‘small’ object whereas for an ‘extended’ object it may not. What is the qualitative meaning of ‘small’ and ‘extended’ in this regard? For which of the following the two coincides? A building, a pond, a lake, a mountain?

The geometric centre of gravity is the geometric centre, but the mass of the place where the complete mass of the body is considered is the mass of the centre of mass. When an object's vertical...

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The net external torque on a system of particle about any axis is zero. Which of the following are compatible with it?
a) the forces may be acting radially from a point on the axis
b) the forces may be acting on the axis of rotation
c) the forces may be acting parallel to the axis of rotation
d) the torque caused by some forces may be equal and opposite to that caused by other forces

When net external torque on a system of particles about an axis is zero, torque is the cross prodeuct of $\vec r$ and $\vec F = rFsin\theta \times torque=0$ where, $\theta$ is the amgle between the...

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Figure shows two identical particles 1 and 2, each of mass m, moving in opposite directions with the same speed v along parallel lines. At a particular instant, r_{1} and r_{2} are their respective positions vectors drawn from point A which is in the plane of the parallel lines. Choose the correct options:
a) angular momentum l_{1} of particle 1 is about A is l_{1} =mvd_{1}
b) angular momentum l_{2} of particle 2 about A is l_{2} = mvx_{2}
c) total angular momentum of the system about A is l = mv(r_{1}+r{2})
d) total angular momentum of the system about A is l = mv(d_{2}-d_{1})

Solution: Correct answers is: d) total angular momentum of the system about A is $l = mv(d_{2}-d_{1})$ Angular momentum of particle 1 about A is given as, $\vec L_1=mvd_1$ Angular momentum of...

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Remark on every one of the accompanying perceptions: (a) The mobilities of the salt metal particles in fluid arrangement are Li+ < Na+ < K+ < Rb+ < Cs+ (b) Lithium is the main metal to frame a nitride straightforwardly. (c)

    \[E0\text{ }for\text{ }M2+\left( aq \right)\text{ }+\text{ }2e\to \text{ }M\left( s \right)\text{ }\left( where\text{ }M\text{ }=\text{ }Ca,\text{ }Sr\text{ }or\text{ }Ba \right)\]

is almost steady.

Solution: (a) The ionic and nuclear sizes of the metals will in general increment while going down the antacid gathering. The expanding request of the ionic sizes of the salt metal particles is as...

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An understudy neglected to add the response blend to the round lined cup at 27 °C however rather he/she set the flagon on the fire. After a pass of time, he understood his error, and utilizing a pyrometer he discovered the temperature of the carafe was 477 °C. What part of air would have been removed out?

solution: Leave the volume of the round lined cup alone V.   Then, at that point, the volume of air inside the cup at 27° C is V.   Presently, \[\begin{array}{*{35}{l}} ~  \\ V1\text{...

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In an experiment to estimate the size of a molecule of oleic acid, 1mL of oleic acid is dissolved in 19mL of alcohol. Then 1mL of this solution is diluted to 20mL by adding alcohol. Now, 1 drop of this diluted solution is placed on water in a shallow trough. The solution spreads over the surface of water forming one molecule thick layer. Now, lycopodium powder is sprinkled evenly over the film we can calculate the thickness of the film which will give us the size of oleic acid molecule.
Read the passage carefully and answer the following questions:
a) Why do we dissolve oleic acid in alcohol?
b) What is the role of lycopodium powder?

a) Because oleic acid does not dissolve in water, it is dissolved in alcohol. b) When oleic acid is introduced, lycopodium powder clears the circular area. This makes it possible to measure the area...

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An artificial satellite is revolving around a planet of mass M and radius R, in a circular orbit of radius r. From Kepler’s third law about the period of a satellite around a common central body, square of the period of revolution T is proportional to the cube of the radius of the orbit r. Show using dimensional analysis, that T = k/R √r3/g where k is a dimensionless constant and g is acceleration due to gravity.

Kepler's third law states that, $T^{2} \propto a^{3}$ i.e., square of time period $\left(T^{2}\right)$ of a satellite revolving around a planet, is proportional to the cube of the radius of the...

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The tension of 1 g of an ideal gas An at 27 °C is observed to be 2 bar. At the point when 2 g of one more ideal gas B is presented in a similar flagon at a similar temperature the strain becomes 3 bar. Discover a connection between their sub-atomic masses.

Solution: \[\begin{array}{*{35}{l}} Mass\text{ }of\text{ }gas\text{ }A\text{ },\text{ }WA~=\text{ }1g  \\ ~  \\ Mass\text{ }of\text{ }gas\text{ }B,~\text{ }WB~=\text{ }2g  \\ ~  \\ Tension\text{...

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The volume of a liquid flowing out per second of a pipe of length l and radius r is written by a student as v=\frac{\pi}{8}\times \frac{Pr^{4}}{\eta l} where P is the pressure difference between the two ends of the pipe and η is coefficient of viscosity of the liquid having dimensional formula ML^{-1}T^{-1}. Check whether the equation is dimensionally correct.

Dimension of the given physical quantity is as follows, [V] = dimension of volume/dimension of time $=[L^{3}]/[T]$ $=[M^{-1}T^{-2}]$ LHS $=[L^{3}T^{-1}]$ RHS $=[L^{3}T^{-1}]$ LHS = RHS Hence, the...

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(a) The earth-moon distance is about 60 earth radius. What will be the diameter of the earth (approximately in degrees) as seen from the moon?
(b) Moon is seen to be of (½)° diameter from the earth. What must be the relative size compared to the earth?

(a) Because the distance between the moon and the earth is greater than the radius of the earth, it is considered as an arc. Let the length of the arc be $R_{e}$ Distance between the moon and the...

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If Planck’s constant (h) and speed of light in vacuum (c) are taken as two fundamental quantities, which of the following can, also, be taken to express length, mass, and time in terms of the three chosen fundamental quantities?
a) mass of the electron (m_{e})
b) universal gravitational constant (G)
c) charge of the electron (e)
d) mass of proton (m_{p})

Correct answers are a) mass of electron b) universal gravitational constant and d) mass of proton

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Pressure versus volume graph for a real gas and an ideal gas is shown in Fig. 5.4. Answer the following questions based on this graph. (i) Interpret the behaviour of real gas with respect to an ideal gas at low pressure. (ii) Interpret the behaviour of real gas with respect to an ideal gas at high pressure. (iii)Mark the pressure and volume by drawing a line at the point where real gas behaves as an ideal gas.

(i) At low pressure as the dark blue curve and the sky blue curve are approaching each other, it shows that the real gas is behaving as an ideal gas at a low pressure. (ii) At high pressure as the...

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The variation of pressure with the volume of the gas at different temperatures can be graphically represented as shown in Fig. 5.3. Based on this graph answer the following questions. (i) How will the volume of a gas change if its pressure is increased at constant temperature? (ii) At constant pressure, how will the volume of a gas change if the temperature is increased from 200K to 400K?

(i) As the temperature is constant, and the pressure is increasing and the change in the volume is seen as exponentially decreasing. (ii) At constant pressure, by increasing the temperature there is...

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The viscosity of a liquid arises due to strong intermolecular forces existing between the molecules. Stronger the intermolecular forces, greater is the viscosity. Name the intermolecular forces existing in the following liquids and arrange them in the increasing order of their viscosities. Also, give a reason for the assigned order in one line. Water, hexane (CH3CH2CH2CH2CH2CH3), glycerine (CH2 OH CH(OH) CH2 OH)

Water has hydrogen bonding that exists as intermolecular force of attraction, hexane has Vander Waal force of attraction existing as intermolecular force of attraction, glycerin also has hydrogen...

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A mass attached to a spring is free to oscillate, with angular velocity \omega, in a horizontal plane without friction or damping. It is pulled to a distance x_{0} and pushed towards the centre with a velocity v_{0} at time t=0 . Determine the amplitude of the resulting oscillations in terms of the parameters \omega, x_{0} and v_{0} . [Hint: Start with the equation x=a \cos (\omega t+\theta) and note that the initial velocity is negative.]

The angular velocity of the spring be $\omega$ $x=a \cos (\omega t+\theta)$ At $t=0, x=x_{0}$ On Substituting these values in the above equation we get, $\mathrm{x}_{0}=\mathrm{A} \cos \theta-(1)$...

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The relation between the pressure exerted by an ideal gas (Pideal) and observed pressure (Pearl) is given by the equation: Pideal = Preal+ an2/V2 If the pressure is taken in Nm-2, the number of moles in mol and volume in m3, Calculate the unit of ‘a’. What will be the unit of ‘a’ when pressure is in atmosphere and volume in dm3?

We know that: Pideal = Preal + an2/V2 Pideal – Preal= an2/V2 Nm-2 = a*mol2/m6 A = Nm4mol-2 The unit of ‘a’ when the pressure is taken in Nm-2, number of moles in “mol” and volume in m3 is Nm4mol-2...

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For real gases the relation between p, V and T are given by van der Waals equation: [(P + an2) / V2](V – nb) = nRT Where‘a’ and ‘b’ are van der Waals constants, ‘nb’ is approximately equal to the total volume of the molecules of a gas. ‘a’ is the measure of the magnitude of intermolecular attraction. (i) Arrange the following gases in the increasing order of ‘b’. Give reason. O2, CO2, H2, He (ii) Arrange the following gases in the decreasing order of magnitude of ‘a’. Give reason. CH4, O2, H2

(i) The increasing order of ‘b’ is as follows: He < H2< O2< CO2. As the Vander Waals constant ‘b’ is approximately equal to the total volume of the molecules of a gas. (ii)The decreasing...

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A circular disc of mass 10 \mathrm{~kg} is suspended by a wire attached to its centre. The wire is twisted by rotating the disc and released. The period of torsional oscillations is found to be 1.5 s. The radius of the disc is 15 \mathbf{c m}. Determine the torsional spring constant of the wire. (Torsional spring constant \alpha is defined by the relation \mathrm{J}=-\alpha \theta, where \mathrm{J} is the restoring couple and \theta the angle of twist).

Mass of the circular disc is given as $10 \mathrm{~kg}$ Period of torsional oscillation is given as $1.5 \mathrm{~s}$ Radius of the disc is given as $15 \mathrm{~cm}=0.15 \mathrm{~m}$ Restoring...

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You are riding in an automobile of mass 3000 \mathrm{~kg}. Assuming that you are examining the oscillation characteristics of its suspension system. The suspension sags 15 \mathrm{~cm} when the entire automobile is placed on it. Also, the amplitude of oscillation decreases by 50 \% during one complete oscillation. Estimate the values of (a) the spring constant \mathbf{k} and (b) the damping constant b for the spring and shock absorber system of one wheel, assuming that each wheel supports 750 \mathrm{~kg}.

(a) Mass of the automobile is given as $=3000 \mathrm{~kg}$ The suspension sags by a length of $15 \mathrm{~cm}$ Decrease in amplitude $=50 \%$ during one complete oscillation If each spring's...

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One end of a U-tube containing mercury is connected to a suction pump and the other end to atmosphere. A small pressure difference is maintained between the two columns. Show that, when the suction pump is removed, the column of mercury in the U-tube executes simple harmonic motion.

Area of cross-section of the U-tube is given as $A$ Density of the mercury column is given as $\rho$ Acceleration due to gravity is given as $g$ Restoring force, F = Weight of the mercury column of...

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A simple pendulum of length I and having a bob of mass M is suspended in a car. The car is moving on a circular track of radius \mathbf{R} with a uniform speed \mathbf{v} . If the pendulum makes small oscillations in a radial direction about its equilibrium position, what will be its time period?

The centripetal acceleration supplied by the circular motion of the car, as well as the acceleration due to gravity, will be felt by the bob of the basic pendulum. Acceleration due to gravity is...

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Answer the following questions:
(a) Time period of a particle in SHM depends on the force constant k and mass m of the particle: \mathbf{T}==2 \pi(\sqrt{m} / \sqrt{k}). A simple pendulum executes SHM approximately. Why then is the time period of a pendulum independent of the mass of the pendulum?
(b) The motion of a simple pendulum is approximately simple harmonic for small-angle oscillations. For larger angles of oscillation, a more involved analysis shows that \mathbf{T} is greater than 2 \pi(\sqrt{I} / \sqrt{g}) . Think of a qualitative argument to appreciate this result.

(a) The spring constant $k$ is proportional to the mass in the case of a simple pendulum. The numerator ($m$) and denominator ($d$) will cancel each other out. As a result, the simple pendulum's...

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Figure (a) shows a spring of force constant k clamped rigidly at one end and a mass \mathbf{m} attached to its free end. A force F applied at the free end stretches the spring. Figure (b) shows the same spring with both ends free and attached to a mass m at either end. Each end of the spring in Fig. (b) is stretched by the same force F.

(a) What is the maximum extension of the spring in the two cases? (b) If the mass in Fig. (a) and the two masses in Fig. (b) is released, what is the period of oscillation in each case? Solution:...

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Plot the corresponding reference circle for each of the following simple harmonic motions. Indicate the initial (t=0) position of the particle, the radius of the circle, and the angular speed of the rotating particle. For simplicity, the sense of rotation may be fixed to be anticlockwise in every case: ( x is in cm and \mathrm{t} is in \mathrm{s}).
(a) x=3 \sin (2 \pi t+\pi / 4)(b) x=2 \cos \pi t

(a)$x=3 \sin (2 m t+\pi / 4)$ $=-3 \cos (2 \pi t+\pi / 4+\pi / 2)$ $=-3 \cos (2 \pi t+3 \pi / 4)$ $=-3 \cos (2 \pi t+3 \pi / 4)$ On comparing with the standard equation $A \cos (\omega t+\Phi)$, we...

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In the given figure, let us take the position of mass when the spring is unstreched as x=0, and the direction from left to right as the positive direction of x-axis. Give x as a function of time t for the oscillating mass if at the moment we start the stopwatch (t =0), the mass is
(a) at the mean position,
(b) at the maximum stretched position.

Solution: Distance travelled by the mass sideways is given as $a=2.0 \mathrm{~cm}$ Angular frequency of oscillation can be calculated as, $\omega=\sqrt{k} / \mathrm{m}$ $=\sqrt{1200 / 3}$...

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The motion of a particle executing simple harmonic motion is described by the displacement function, x(t)=A \cos (\omega t+\varphi) If the initial (t =0 ) position of the particle is 1 \mathrm{~cm} and its initial velocity is \omega \mathrm{cm} / \mathrm{s}, what are its amplitude and initial phase angle? The angular frequency of the particle is \pi \mathrm{s}^{-1}. If instead of the cosine function, we choose the sine function to describe the SHM: x=B \sin (w t+a), what are the amplitude and initial phase of the particle with the above initial conditions. Solution:

At positlon, t = 0, The given function is $x(t)=A \cos (\omega t+\phi).....(1)$ $\begin{array}{l} 1=A \cos (\omega \times 0+\phi)=A \cos \phi \\ A \cos \phi=1 \end{array}$ Differentiating equation...

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A particle is in linear simple harmonic motion between two points, A and B, 10 \mathrm{~cm} apart. Take the direction from A to B as the positive direction and give the signs of velocity, acceleration and force on the particle when it is
(a) at the mid-point of AB going towards A,
(b) at 2 \mathbf{c m} away from B going towards A

(a) Negative, Zero, Zero A basic harmonic motion is being performed by the particle. The particle's mean location is denoted by $O$. Its highest velocity is at the mean position $O$. Because the...

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A particle is in linear simple harmonic motion between two points, A and B, 10 \mathrm{~cm} apart. Take the direction from A to B as the positive direction and give the signs of velocity, acceleration and force on the particle when it is
(a) at the end A,
(b) at the end B

(a) Zero, Positive, Positive Points A and B are the path's two ends, with A-B=10cm and'O' being the path's halfway. Between the end locations, a particle moves in a linear simple harmonic motion....

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Which of the following examples represent (nearly) simple harmonic motion and which represent periodic but not simple harmonic motion?
(a) motion of a ball bearing inside a smooth curved bowl, when released from a point slightly above the lower most point.
(b) general vibrations of a polyatomic molecule about its equilibrium position.

(a) Simple harmonic motion (b) SHM is not periodic, although general vibrations of a polyatomic molecule about its equilibrium position are. The inherent frequencies of a polyatomic molecule are...

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Two different gases ‘A’ and ‘B’ are filled in separate containers of equal capacity under the same conditions of temperature and pressure. On increasing the pressure slightly the gas ‘A’ liquefies but gas B does not liquefy even on applying high pressure until it is cooled. Explain this phenomenon.

The critical temperature is the term used for this phenomenon. Here gas A liquefies means that A is below its critical temperature and gas B does not liquefy on applying high pressure as it is above...

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Use the information and data given below to answer the questions (a) to (c): • Stronger intermolecular forces result in a higher boiling point. • Strength of London forces increases with the number of electrons in the molecule. • Boiling point of HF, HCl, HBr and HI is 293 K, 189 K, 206 K and 238 K respectively. (a) Which type of intermolecular forces are present in the molecules HF, HCl, HBr and HI? (b) Looking at the trend of boiling points of HCl, HBr and HI, explain out of dipole-dipole interaction and London interaction, which one is predominant here. (c) Why is the boiling point of hydrogen fluoride highest while that of hydrogen chloride lowest?

(a) Since the halides are a polar molecule (due to high electronegativity), due to the presence of permanent dipoles, the dipole-dipole interactions along with the London forces are found in HF, HCl...

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A man standing at a certain distance from an observer blows a horn of frequency 200 \mathrm{~Hz} in still air.
(a) Find the horn’s frequency for the observer when the man (i) runs towards him at 20 \mathrm{~m} / \mathrm{s} (ii) runs away from him at \mathbf{2 0} \mathrm{m} / \mathrm{s}.
(b) Find the speed of sound in both the cases.
[Speed of sound in still air is \mathbf{3 4 0 \mathrm { m } / \mathrm { s } \text { ] }}

Frequency of the horn is given as $\mathrm{v}_{\mathrm{H}}=200 \mathrm{~Hz}$ Velocity of the man is given as $\mathrm{v}_{\mathrm{T}}=20 \mathrm{~m} / \mathrm{s}$ Velocity of sound is given as...

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Earthquakes generate sound waves inside the earth. Unlike a gas, the earth can experience both transverse (S) and longitudinal (P) sound waves. Typically the speed of the S wave is about 4.0 \mathrm{~km} \mathrm{~s}^{-1}, and that of the \mathrm{P} wave is 8.0 \mathrm{~km} \mathrm{~s}^{-1}. A seismograph records \mathrm{P} and \mathrm{S} waves from an earthquake. The first P wave arrives 4 min before the first S wave. Assuming the waves travel in a straight line, at what distance does the earthquake occur?

Let $S$ and $P$ have speeds of $v_{1}$ and $v_{2}$, respectively. The $S$ and $P$ waves take $t_{1}$ and $t_{2}$ seconds to reach the position of the seismograph, respectively. $I=v_{1} t_{1}=v_{2}...

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One end of a long string of linear mass density 8.0 \times 10^{-3} \mathrm{~kg} \mathrm{~m}^{-1} is connected to an electrically driven tuning fork of frequency 256 \mathrm{~Hz}. The other end passes over a pulley and is tied to a pan containing a mass of 90 \mathrm{~kg}. The pulley end absorbs all the incoming energy so that reflected waves at this end have negligible amplitude. At t=0, the left end (fork end) of the string x=0 has zero transverse displacement (y=0) and is moving along positive y-direction. The amplitude of the wave is 5.0 \mathrm{~cm}. Write down the transverse displacement y as a function of x and t that describes the wave on the string.

Linear mass density of the string is given as $\mu=8.0 \times 10^{-3} \mathrm{~kg} \mathrm{~m}^{-1}$ Frequency of the tuning fork is given as $=256 \mathrm{~Hz}$ Mass on the pan is given as $90...

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A travelling harmonic wave on a string is described by y(x, t)=7.5 \sin (0.0050 x+12 t+m / 4)
(a) What are the displacement and velocity of oscillation of a point at x=1 \mathrm{~cm}, and t=1 \mathrm{~s} ? Is this velocity equal to the velocity of wave propagation?
(b) Locate the points of the string which have the same transverse displacements and velocity as the x=1 \mathrm{~cm} point at t=2 \mathrm{~s}, \mathbf{5} \mathrm{s} and 11 \mathrm{~s}

(a) The travelling harmonic wave is given by, $y(x, t)=7.5 \sin (0.0050 x+12 t+\pi / 4)$ At $x=1 \mathrm{~cm}$ and $\mathrm{t}=1 \mathrm{~s}$ $y(1,1)=7.5 \sin (0.0050(1)+12(1)+\pi / 4)$ $=7.5 \sin...

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A train, standing at the outer signal of a railway station blows a whistle of frequency 400 \mathrm{~Hz} in still air. (i) What is the frequency of the whistle for a platform observer when the train (a) approaches the platform with a speed of 10 \mathrm{~m} \mathrm{~s}^{-1}, (b) recedes from the platform with a speed of 10 \mathrm{~m} \mathrm{~s}^{-1} ? (ii) What is the speed of sound in each case? The speed of sound in still air can be taken as \mathbf{3 4 0} \mathrm{m} \mathrm{s}^{-1}.

Frequency of the whistle is given as $=400 \mathrm{~Hz}$ Speed of sound in still air is given as $=340 \mathrm{~m} / \mathrm{s}$ (i) (a)Train approaches the platform at a speed given as...

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Explain how:
(i) A guitar note and violin note are being played at the same frequency, however, we can still make out which instrument is producing which note
(ii) Both transverse and longitudinal wave can propagate through solids, but only longitudinal waves can move through gases.

(i) Overtones are produced differently by the guitar and the violin. Even though the notes from a guitar and a violin vibrate at the same frequencies, it is possible to distinguish between them....

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The transverse displacement of a wire (clamped at both its ends) is described as : y(x, t)=0.06 \sin \left(\frac{2 \pi}{3} x\right) \cos (120 \pi t) The mass of the wire is 6 \times 10^{-2} \mathrm{~kg} and its length is 3 \mathrm{~m}.
Provide answers to the following questions:
(i) Is the function describing a stationary wave or a travelling wave?
(ii) Interpret the wave as a superposition of two waves travelling in opposite directions. Find the speed, wavelength and frequency of each wave.

As we know, The standard equation of a stationary wave is known as, $y(x, t)=2 a \sin k x \cos w t$ Given equation is, $y(x, t)=0.06 \sin \left(\frac{2 \pi}{3} x\right) \cos (120 \pi t)$ It is...

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Gases possess characteristic critical temperature which depends upon the magnitude of intermolecular forces between the particles. Following are the critical temperatures of some gases. Gases H2 He O2 N2 Critical temperature in Kelvin 33.2 5.3 154.3 126 From the above data what would be the order of liquefaction of these gases? Start writing the order from the gas liquefying first (i) H2, He, O2, N2 (ii) He, O2, H2, N2 (iii) N2, O2, He, H2 (iv) O2, N2, H2, He

The correct option is (iv) O2, N2, H2, He.

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Which of the following statements is correct? (i) Metallic hydrides are deficient of hydrogen. (ii) Metallic hydrides conduct heat and electricity. (iii) Ionic hydrides do not conduct electricity in solid-state. (iv) Ionic hydrides are very good conductors of electricity in solid-state.

Solution: Option (i), (ii) and (iii) are the answers. Metallic hydrides are hydrides that are not stoichiometric in nature. They are excellent conductors of heat and electricity. Ionic hydrides...

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