Tag: physics

Questions Related to physics

4.0 g of a gas occupies 22.4 litres at NTP. The specific heat capacity of the gas at constant volume is 5.0 ${ JK }^{ -1 }{ mol }^{ -1 }$. If the speed of sound in this gas at NTP is 952${ ms }^{ -1 }$, then the heat capacity at constant pressure is (Take gas constant R=8.3${ JK }^{ -1 }{ mol }^{ -1 }$)

principal and molar specific heats of gases isothermal and adiabatic processes specific heat capacity heat and thermodynamics physics

  1. $8.5{ JK }^{ -1 }{ mol }^{ -1 }$

  2. $8.0{ JK }^{ -1 }{ mol }^{ -1 }$

  3. $7.5{ JK }^{ -1 }{ mol }^{ -1 }$

  4. $7.0{ JK }^{ -1 }{ mol }^{ -1 }$

Show answer
Correct Option: B

When an ideal diatomic gas is heated at a constant pressure, the fraction of the heat energy supplied which increases the internal energy of the gas is

principal and molar specific heats of gases isothermal and adiabatic processes specific heat capacity heat and thermodynamics physics

  1. $\dfrac {2}{5}$

  2. $\dfrac {3}{5}$

  3. $\dfrac {3}{7}$

  4. $\dfrac {5}{7}$

Show answer
Correct Option: D
Explanation:

$Th\quad fraction\quad is\quad \frac { \triangle V }{ \triangle Q } \quad =\quad \frac { { _{ n }{ C } _{ v } }\triangle T }{ { _{ n }{ C } _{ p } }\triangle T } \ \frac { \triangle V }{ \triangle Q } =\frac { { C } _{ V } }{ { C } _{ P } } \quad =\quad \frac { 1 }{ Y } \ as\quad we\quad know\quad y\quad =\quad { C } _{ P }/{ C } _{ V }\ y\quad for\quad diatomatic\quad gas\quad :\quad \ { C } _{ P }\quad of\quad diatometic\quad gas\quad :\quad \frac { 7 }{ 2 } \ { C } _{ V }\quad of\quad diatometic\quad gas\quad :\quad \frac { 5 }{ 2 } \ y\quad =\quad \frac { { C } _{ P } }{ { C } _{ V } } =\frac { 7/2 }{ 5/2 } =\frac { 7 }{ 5 } \ \frac { \triangle V }{ \triangle Q } =\frac { 1 }{ y } =\frac { 1 }{ 7/5 } =\frac { 5 }{ 7 } \quad (D)$

For an ideal gas, the heat capacity at constant pressure is larger than that at constant volume because

principal and molar specific heats of gases isothermal and adiabatic processes specific heat capacity heat and thermodynamics physics

  1. positive work is done during expansion of the gas by the external pressure

  2. positive work is done during expansion by the gas against external pressure

  3. positive work is done during expansion by the gas against intermolecular forces of attraction

  4. more collisions occur per unit time when volume is kept constant

Show answer
Correct Option: B
Explanation:

When  heat  is  supplied  at  constant  volume,  temperature  increases accordingly  to  the  ideal  gas  equation.

$P=\dfrac { nRT }{ V } $

as  V  is  constant  and  T  is  increasing,  pressure  will  also  increase.

Than at constant pressure  as temperature is increase volume increases, resulting in expansion of the gas, resulting in positive work, Hence the heat given is used up for expansion and then to increases the internal energy . The heat capacity at constant pressure is larger.

A transverse wave on a string has an amplitude of $02m$ and a frequency of $175Hz$. Consider a particle of the string at $x=0$. It begins with a displacement $y=0$ at $t=0$, according to equation $y=0.2\sin{(kx+\omega t)}$. How much time passes between the first two instant when this particle has a displacement of $y=0.1m$>

physics wave motion wave velocity speed and acceleration of travelling wave speed of a travelling wave

  1. $1.9ms$

  2. $3.9ms$

  3. $2.4ms$

  4. $0.5ms$

Show answer
Correct Option: C

For a string clamped at both its ends, which of the following wave equation is/are valid for a stationary wave set up in it? (Origin is at one end of string).

physics wave motion wave velocity speed and acceleration of travelling wave speed of a travelling wave

  1. $y=A\sin kx.\sin \omega t$

  2. $y=A\cos kx \sin \omega t$

  3. $y=A\sin kx. \cos \omega t$

  4. $y=A\cos kx \cos \omega t$

Show answer
Correct Option: A,C
Explanation:

For all values of t, y$=0$ at $x=0$
Hence, (A) and (C) are correct.

In transverse wave the distance between a crest and through at the same place is 1.0 cm. The next crest appears at the same place after a time interval of 0.4 s. The maximum speed of the vibrating particles in the same medium is :

physics wave motion wave velocity speed and acceleration of travelling wave speed of a travelling wave

  1. $\dfrac{3\pi }{2}cm/s$

  2. $\dfrac{5\pi }{2}cm/s$

  3. $\dfrac{\pi }{2}cm/s$

  4. $2\pi cm/s$

Show answer
Correct Option: A

A certain strings will resonate to several frequencies , the lowest of which is $200$cps.what are the next three higher frequencies to which it resonates? 

physics wave motion wave velocity speed and acceleration of travelling wave speed of a travelling wave

  1. $400,600,800$

  2. $300,400,500$

  3. $100,150,200$

  4. $200,250,300$

Show answer
Correct Option: A
Explanation:
Given,  The Lowest frequency is $200cps$

Let  $f$ resonant the fundamental frequency, then the next higher frequency is: $2f,3f,4f$

$2\times200=400cps,3\times200=600,4\times200=800cps$


The string of a violin emits a note of 205 Hz at its correct tension. The string is tightened slightly and then it produces six beats in two seconds with a tuning fork of frequency 205 Hz. The frequency of the note emitted by the taut string is

physics wave motion wave velocity speed and acceleration of travelling wave speed of a travelling wave

  1. 211 HZ

  2. 199 Hz

  3. 208 Hz

  4. 202 Hz

Show answer
Correct Option: A

A wire stretched between two rigid supports vibrates in its fundamental mode with a frequency of $45 Hz$. The mass of the wire is $3.5 \times 10^{-2}kg$ and its linear mass density is $4.0 \times 10^{-2} kgm^{-1}$. What is the speed of a transverse wave on the wire?

physics wave motion wave velocity speed and acceleration of travelling wave speed of a travelling wave

  1. $69 \ ms^{-1}$

  2. $79 \ ms^{-1}$

  3. $89 \ ms^{-1}$

  4. $99 \ ms^{-1}$

Show answer
Correct Option: B

A person observe two points on a string as a travelling wave passes them. The points are at $x _ { 1 } = 0$ and $x _2 = 1m$. The transverse motions of the two points are found to be as follows: $y _ { 1 } = 0.2 \sin 3 \pi t$
$y _ { 2 } = 0.2 \sin ( 3 \pi t + \pi/8 )$ What is the frequency in Hertz?

physics wave motion wave velocity speed and acceleration of travelling wave speed of a travelling wave

  1. $1.5 Hz$

  2. $3 Hz$

  3. $4.5 Hz$

  4. $1 Hz$

Show answer
Correct Option: A