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aniked [119]
3 years ago
14

The latent heat of fusion of alcohol is 25 kcal/kg and its melting point is -114 o C. It has a specific heat of 0.60 in its liqu

id state. Calculate the energy needed to melt 2.0 kg of solid alcohol at -114 o C and raise it to a temperature of -14 o C.
A) 70 kcal
B) 120 kcal
C) 170 kcal
D) 220 kcal
Physics
1 answer:
Elanso [62]3 years ago
4 0

Answer:

Total energy is 170 kJ

Explanation:

Given data:

latent heat of fusion of alcohol is 25 kcal/kg

melting point of alcohol is -114 degree c

specific heat us 0.60 k cal/kg degree c

energy need for 2 kg solid alcohol is

for Melting:

Energy Q is calculated as

Energy, Q = 25 \times 2.0 kg = 50 kJ

Energy required for Heating liquid:

Energy, ΔH = 2.0 kg \times 0.60 \times (100°C) = 120 kJ

Total  energy = (50 kJ + 120 kJ) = 170 kJ

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A cyclical heat engine, operating between temperatures of 450º C and 150º C produces 4.00 MJ of work on a heat transfer of 5.00
gogolik [260]

Answer:

(a) Heat transfer to the environment is: 1 MJ and (b) The efficiency of the engine is: 41.5%

Explanation:

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7 0
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A bucket of water of mass 10 kg is pulled at constant velocity up to a platform 30 meters above the ground. This takes 10 minute
Rudik [331]

Answer:

W = 2352 J

Explanation:

Given that:

  • mass of the bucket, M = 10 kg
  • velocity of pulling the bucket, v = 3m.min^{-1}
  • height of the platform, h = 30 m
  • time taken, t = 10 min
  • rate of loss of water-mass, m = 0.4 kg.min^{-1}

Here, according to the given situation the bucket moves at the rate,

v=3 m.min^{-1}

The mass varies with the time as,

M=(10-0.4t) kg

Consider the time interval between t and t + ∆t. During this time the bucket moves a distance

∆x =  3∆t meters

So, during this interval change in work done,

∆W = m.g∆x

<u>For work calculation:</u>

W=\int_{0}^{10} [(10-0.4t).g\times 3] dt

W= 3\times 9.8\times [10t-\frac{0.4t^{2}}{2}]^{10}_{0}

W= 2352 J

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