Tag: physics

Questions Related to physics

The ratio $(v)$ of velocities of sound in dry air and humid air is

physics propagation of sound waves sound as a wave of disturbance vibrations in a tuning fork vibrations in tuning fork

  1. $v<1$

  2. $v>1$

  3. $v=1$

  4. Zero

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Correct Option: A
Explanation:

Because water molecules have less mass than the average air molecules $(N _2 (28 \text{amu}),$ while water $H _2O (18 amu)).$ But It will happen if and only if the pressure is unchanged. Given that dry and humid air are both under the same pressure then we have smaller density for humid air.
And velocity of sound waves$,v,$ in a medium is given by,


$v=\sqrt{\dfrac{\gamma E}{d}}$, here $\gamma = \dfrac{C _P}{C _V}$, 

$E$ is elasticity of the medium, and $d$ is the density.

Since, density of air decreases with humidity increases. therefore velocity of sound increases in humid air.
Option "A" is correct.

A rope length $\displaystyle l$ and mass $\displaystyle m$ hanges freely from the ceiling. The velocity of transverse wave as a function of position $\displaystyle x$ along the rope is proportional to

physics sound sound as a wave of disturbance vibrations in a tuning fork vibrations in tuning fork

  1. 1 / $\displaystyle \sqrt x$

  2. $\displaystyle \sqrt x$

  3. $\displaystyle x$

  4. $\displaystyle x^0$

Show answer
Correct Option: B
Explanation:

$\text{Mass per unit length of rope} =\dfrac{m}{l}$
Mass of rope of length $x =\dfrac { m }{ l } x$
Tension, $T = \dfrac { m }{ l } xg$
Velocity, $v=\sqrt { \dfrac { T }{ m }  } =\sqrt { \dfrac { mgl }{ lm } x }$      which is directly proportional to $\sqrt { x } $

When the stem of a vibrating tuning fork is pressed a sounding board, then

physics vibrations of stretched strings sound as a wave of disturbance vibrations in a tuning fork vibrations in tuning fork

  1. transverse vibrations are communicated through stem to the board.

  2. longitudinal vibrations are communicated through stem to the board

  3. both longitudinal and transverse vibrations are communicated through stem on the board

  4. none of the above

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Correct Option: B
Explanation:

When the tuning fork is set into vibration, the stem of tuning fork vibrate  up and down with longitudinal vibrations hence, when the stem of a vibrating tuning fork is pressed a sounding board, then longitudinal vibrations are communicated through stem to the board.

When slinky is stretched out in a horizontal direction and first coils are vibrated horizontally then which waves are generated?

physics sound sound as a wave of disturbance vibrations in a tuning fork vibrations in tuning fork

  1. Longitudinal Waves

  2. Transverse Waves

  3. Surface waves 

  4. None

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Correct Option: A
Explanation:

Longitudinal Waves are generated when slinky is stretched out in a horizontal direction and first coils are vibrated horizontally 

The moving striker of the carom board will possess------ energy

physics work, energy and power forms of energy and energy conservation energy for everything forms of energy

  1. Kinetic

  2. Potential

  3. Solar

  4. Electric

Show answer
Correct Option: A
Explanation:

as the striker is moving it will possess kinetic enegry

Geothermal energy is feasible in regions that

physics work, energy and power forms of energy and energy conservation energy for everything forms of energy

  1. Are near the sea

  2. Have thermal plants

  3. Have coal mines

  4. Are over hot spots in the crust

Show answer
Correct Option: D

A charged parallel plate capacitor of distance ($d$) has ${U} _{0}$ energy. A slab of dielectric constant ($K$) and thickness ($d$) is then introduced between the plates of the capacitor. The new energy of the system is given by:

physics energy transformations and energy transfers forms of energy and energy conservation energy for everything forms of energy

  1. $K{U} _{0}$

  2. ${K}^{2}{U} _{0}$

  3. $\cfrac{{U} _{0}}{K}$

  4. $\cfrac{{U} _{0}}{{K}^{2}}$

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Correct Option: B

 person trying to lose weight by burning fat lifts a mass of $10kg$ upto a height of $0.5\, m\, with\, in\, 1000$ times. Assume that the potential energy lost each time he lowers the mass is dissipated. How much fat will he use up considering the work done only when the weight is lifted up? Fat supplies $3.8 \times 10^7 J$ of energy per kg which is converted to mechanical energy with a $20 \%$ efficiency rate. 

physics energy transformations and energy transfers forms of energy and energy conservation energy for everything forms of energy

  1. $6.45 \times {10^{ - 3}}kg$

  2. $9.89 \times {10^{ - 3}}kg$

  3. $12.89 \times {10^{ - 3}}kg$

  4. $2.45 \times {10^{ - 3}}kg$

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Correct Option: A

When water falls from a height, the energy changes from,

physics energy transformations and energy transfers forms of energy and energy conservation energy for everything forms of energy

  1. kinetic to potential

  2. potential to kinetic

  3. chemical to mechanical

  4. Mechanical to chemical

Show answer
Correct Option: B
Explanation:

Potential  to kinetic energy

Corpuscular theory of light was advanced by

physics wave optics wave behaviour huygens wave theory and wavefront wave propagation (huygens' construction)

  1. Huygen

  2. Newton

  3. Maxwell

  4. Hertz

Show answer
Correct Option: B
Explanation:

$Answer:$ B

The corpuscular theory was largely developed by Sir Isaac newton. Newton's theory remained in force for more than 100 years and took precedence over Huygen's wave front theory, partly because of Newton’s great prestige. When the corpuscular theory failed to adequately explain the diffraction, interference and polarization of light it was abandoned in favour of Huygens' wave theory.