Physics Thermodynamics

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New answer posted•a year ago

Physics Thermodynamics Thermodynamics

The enthalpy of combustion of propane, graphite and dihydrogen at 298 K are -2220.0 kJ mol^-1, -393.5kJ mol^-1 and -285.8kJ mol^-1 respectively. The magnitude of the enthalpy of formation of propane C₃H₈ is _________ kJ mol^-1 (Nearest integer)

7 Views|Posted a year ago

Asked by Vishal Baghel

Answered by

Vishal Baghel | Contributor-Level 10

a year ago

3C (Graphite) + 4H₂ (g) -> C₃H₈ (g)

$Δ H_{f} (C_{3} H_{8}) = [3 \times Δ H_{c o m b} (C)] + [4 \times Δ H_{c o m b} (H_{2})] - [Δ H_{c o m b} (C_{3} H_{8})]$

= -10.3.7 kJ/mole

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New answer posted•a year ago

Physics Thermodynamics Thermodynamics

The pressure P₁ and density d₁ of diatomic gas $(γ = \frac{7}{5})$  changes suddenly to P₂(>P₁) and d₂ respectively during an adiabatic process. The temperature of the gas increases and becomes ________times of its initial temperature. (given  $\frac{d_{2}}{d_{1}} = 32)$

2 Views|Posted a year ago

Asked by Vishal Baghel

Answered by

Vishal Baghel | Contributor-Level 10

a year ago

For adiabatic process – PV^Y= const

$T_{1} {V_{1}}^{Y - 1} = T_{2} V_{2}^{Y - 1}$

$\frac{T_{2}}{T_{1}} = {(\frac{v_{1}}{v_{2}})}^{Y - 1} = {(\frac{d_{2}}{d_{1}})}^{Y - 1} = {(32)}^{(\frac{7}{5} - 1)} = {(32)}^{2 / 5}$

$= {(2)}^{2} = 4$

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New answer posted•a year ago

Physics Thermodynamics Class 11th

A steam engine intakes 50g of steam at $100 ° C$  per minute and cools it down to $20 ° C .$  If latent heat of vaporization of steam is 540 cal g^-¹, then the heat rejected by the steam engine per minute is………….× 10³ cal.

(Given : specific heat capacity of water : 1 cal g^-¹ ⁰C^-¹)

5 Views|Posted a year ago

Asked by Payal Gupta

Answered by

Payal Gupta | Contributor-Level 10

a year ago

$Q_{1} = \underset{w a t e r}{20 ° C} \to 100 ° s t e a m$

$Q_{1} = m c Δ T + m L$

$= m [c Δ T + L]$

$= 31000 = 31 \times 1 0^{3} c a l$

$Q_{2} = \frac{293}{373} \times 31 \times 1 0^{3}$

$= 24.35 \times 1 0^{3} c a l$

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New answer posted•a year ago

Physics Thermodynamics Class 11th

In an experiment to verigy Newton’s law of cooling, a graph is plotted between, the temperature difference $(Δ T)$  of the water and surrounding and time as shown in figure. The initial temperature of water is taken as $80 ° C .$  The value of t₂ as mentioned in the graph will be _______.

6 Views|Posted a year ago

Asked by Payal Gupta

Answered by

Payal Gupta | Contributor-Level 10

a year ago

$\frac{d T}{d t} = - k (T - T_{0})$

$\frac{d T}{(T - T_{0})} = - k d t$

$\Rightarrow k = - \frac{1}{6} l n (\frac{2}{3})$ - (1)

Now $\frac{d T}{d t} = - k (T - T_{0})$

t = 10.257

t₂ = 6 + 10.257 = 16.257 minutes

16.25 and or 16

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New answer posted•a year ago

Physics Thermodynamics Class 11th

A monoatomic gas performs a work of $\frac{Q}{4}$ where Q is the heat supplied to it. The molar heat capacity of the gas will be ________ R during this transformation. Where R is the gas constant.

2 Views|Posted a year ago

Asked by Payal Gupta

Answered by

Payal Gupta | Contributor-Level 10

a year ago

$Q = Δ υ + w \Rightarrow n C Δ T = n C_{v} Δ T = \frac{n C Δ T}{4} = \frac{3}{4} n C Δ T = n C_{v} Δ T$

$C = \frac{4}{3} C_{v} = \frac{4}{3} \times \frac{3}{2} R = 2 R$

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New answer posted•a year ago

Physics Thermodynamics Class 11th

A 100g of iron nail is hit by a 1.5 kg hammer striking at a velocity of 60ms^-1. What will be the rise in the temperature of the nail if one fourth of energy of the hammer goes into heating the nail?

17 Views|Posted a year ago

Asked by Payal Gupta

Answered by

Payal Gupta | Contributor-Level 10

a year ago

Heating energy $= \frac{1}{4} t h$ energy of the hammer

$= \frac{1}{4} \times \frac{1}{2} m v^{2}$

$= \frac{1}{4} \times \frac{1}{2} \times 1.5 \times 60 \times 60$

$= \frac{15 \times 6 \times 60}{4 \times 2}$

= 675 J

$Δ T = \frac{675}{42} = 16.07 ° C$

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New answer posted•a year ago

Physics Thermodynamics Thermodynamics

A cornot engine whose heat sinks at 27°C has an efficiency of 25%. By how many degrees should the temperature of the source be changed to increase the efficiency by 100% of the original efficiency?

4 Views|Posted a year ago

Asked by Vishal Baghel

Answered by

Vishal Baghel | Contributor-Level 10

a year ago

0.25 = 1 - $\frac{T_{2}}{T_{1}}$ $\frac{_{}}{_{}}$

0.25 = 1 - $\frac{(27 + 273)}{T_{1}} \Rightarrow \frac{300}{T_{1}} = 1 - 0.25$ $\frac{}{_{}} \frac{}{_{}}$

$\Rightarrow \frac{300}{T_{1}} = 0.75$

$T_{1} = \frac{300 \times 100}{75}$

T1 = 400 k

Now, efficiency increases by 100%

$η_{2} = 100 % η_{1} + η_{1}$

$= 2 η_{1}$

= 0.25 × 2

= 0.50

0.50 = 1 - $\frac{T_{2}'}{T_{1}}$ $\frac{_{}}{_{}}$

$\Rightarrow \frac{T_{2}'}{T_{1}} = 0.50$

$T_{1}' = \frac{300}{0.5}$

$T_{1}' = 600 k$

$T_{1}' - T_{1} =$ (600 – 400) = 200 k or 200° C

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New answer posted•a year ago

Physics Thermodynamics Class 11th

A sample of an ideal gas is taken through the cyclic process ABCA as shown in figure. It absorbs, 40 J of heat during the part AB, no heat during BC and rejects 60 J of heat during CA. A work of 50 J is done on the during the part BC. The internal energy of the gas at A is 1560 J. The work done by the gas during the part CA is:

27 Views|Posted a year ago

Asked by Alok Kumar Singh

Answered by

Alok Kumar Singh | Contributor-Level 10

a year ago

Given &

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New answer posted•a year ago

Physics Thermodynamics Mechanical Engineering

Which is the best Mechanical Engineering book to understand the basics of thermodynamics for beginners?

13 Views|Posted a year ago

Asked by Vidhi Jain

Answered by

Vidhi Jain | Contributor-Level 10

a year ago

One of the most important Mechanical Engineering subjects is Thermodynamics, which deals with the concepts of heat energy and temperature, along with its conversion between different forms. You would come across a variety of books that will give you a basic understanding of the concept, but here are

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New answer posted•a year ago

Physics Thermodynamics Engineering Entrance Exam

I got 1816k/11k rank in XE GATE. My GATE score is of 345+. What are my chances of getting a seat for M.Tech in Thermodynamics stream?

9 Views|Posted a year ago

Asked by Guest

Answered by

Ambika Singh | Contributor-Level 6

a year ago

In GATE XE (Engineering Sciences), Thermodynamics is one of the optional sections (XE-E), but admissions for M.Tech are usually branch-specific (like Mechanical, Thermal, Energy Engineering).

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