Ask question

Ask question

All categories

3 years ago

7

1 kg of oxygen is heated from 20 to 120°C. Determine the amount of heat transfer required when this is done during a (a) constan

t-volume process and (b) isobaric process.

1 answer:

Ahat [919]3 years ago

4 0

(a) At constant-volume, Q = 66.7kJ

(b) At isobaric condition, Q = 92.7kJ

<u>Explanation:</u>

The specific heats of oxygen at the average temperature of (20+120)/2 = 70°C = 343 K are

Cp = 0.927 kJ/kg.K

Cv = 0.667 kJ/kgK

We take the oxygen as the system. This is a closed system since no mass crosses the boundaries of the system. The energy balance for a constant-volume process can be expressed as

ΔE (system) = E(in) - E(out)

and

Q(in) = ΔH = mCp x (T₂ - T₁)

since ΔU + Wb = ΔH during a constant pressure quasi-equilibrium

process. Substituting for both cases,

(a)

Qin,V =const = mCv (T2 - T1 )

= (1kg)(0.667 kJ/kg.K)(120 - 20)K

= 66.7kJ

(b)

Qin,P=const = mCp (T2 - T1 )

= (1kg)(0.927 kJ/kg.K)(120 - 20)K

= 92.7kJ

You might be interested in

Câu 1: Tìm từ trong 2 câu thơ sau liên quan đến các từ: hình chiếu, tia chiếu, mặt phẳng chiếu.

xeze [42]

Explanation:

are bhai brainly aap english me questions kar ne ko hai

ye kon si bhasha hai ??????

4 0

2 years ago

. Using the Newton Raphson method, determine the uniform flow depth in a trapezoidal channel with a bottom width of 3.0 m and si

Over [174]

Answer:

y ≈ 2.5

Explanation:

Given data:

bottom width is 3 m

side slope is 1:2

discharge is 10 m^3/s

slope is 0.004

manning roughness coefficient is 0.015

manning equation is written as

$v =1/n R^{2/3} s^{1/2}$

where R is hydraulic radius

S = bed slope

$Q = Av =A 1/n R^{2/3} s^{1/2}$

$A = 1/2 \times (B+B+4y) \times y =(B+2y) y$

$R =\frac{A}{P}$

P is perimeter $= (B+2\sqrt{5} y)$

$R =\frac{(3+2y) y}{(3+2\sqrt{5} y)}$

$Q = (2+2y) y) \times 1/0.015 [\frac{(3+2y) y}{(3+2\sqrt{5} y)}]^{2/3} 0.004^{1/2}$

solving for y $100 =(2+2y) y) \times (1/0.015) [\frac{(3+2y) y}{(3+2\sqrt{5} y)}]^{2/3} \times 0.004^{1/2}$

solving for y value by using iteration method ,we get

y ≈ 2.5

5 0

3 years ago

A wooden pallet carrying 540kg rests on a wooden floor. (a) a forklift driver decides to push it without lifting it.what force m

kicyunya [14]

Answer:

The appropriate solution is "1481.76 N".

Explanation:

According to the question,

Mass,

m = 540 kg

Coefficient of static friction,

$\mu_s$ = 0.28

Now,

The applied force will be:

⇒ $F=\mu_s mg$

By substituting the values, we get

$=0.28\times 540\times 9.8$

$=1481.76 \ N$

8 0

2 years ago

A cruise missile under test is moving horizontally at Ma =2 in the atmosphere at an elevation of 2000 m (Air temperature is 2 °C

telo118 [61]

Answer: the half-angle "alpha" of the Mach cone = 30⁰

Explanation:

To calculate the half-angle "alpha" of the Mach cone.

we say ;

Sin∝ = 1 / Ma

given that Ma = 2

now we substitute

Sin∝ = 1 / 2

Sin∝ = 0.5

∝ = Sin⁻¹ 0.5

∝ = 30⁰

Therefore, the half-angle "alpha" of the Mach cone is 30⁰

3 0

3 years ago

A small metal particle passes downward through a fluid medium while being subjected to the attraction of a magnetic field such t

bekas [8.4K]

Answer:

a)Δs = 834 mm

b)V=1122 mm/s

$a=450\ mm/s^2$

Explanation:

Given that

$s = 15t^3 - 3t\ mm$

a)

When t= 2 s

$s = 15t^3 - 3t\ mm$

$s = 15\times 2^3 - 3\times 2\ mm$

s= 114 mm

At t= 4 s

$s = 15t^3 - 3t\ mm$

$s = 15\times 4^3- 3\times 4\ mm$

s= 948 mm

So the displacement between 2 s to 4 s

Δs = 948 - 114 mm

Δs = 834 mm

b)

We know that velocity V

$V=\dfrac{ds}{dt}$

$\dfrac{ds}{dt}=45t^2-3$

At t= 5 s

$V=45t^2-3$

$V=45\times 5^2-3$

V=1122 mm/s

We know that acceleration a

$a=\dfrac{d^2s}{dt^2}$

$\dfrac{d^2s}{dt^2}=90t$

a= 90 t

a = 90 x 5

$a=450\ mm/s^2$

4 0

3 years ago