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An engine absorbs 1.69 kJ from a hot reservoir at 277°C and expels 1.25 kJ to a cold reservoir at 27°C in each cycle.

Anna35 [415]

Answer

Given,

Energy absorbed, $Q_H = 1.69\ kJ$

Energy expels, $Q_C = 1.25\ kJ$

Temperature of cold reservoir, T = 27°C

a) Efficiency of engine

$\eta = \dfrac{Q_H - Q_C}{Q_H}\times 100$

$\eta = \dfrac{1.69 - 1.25}{1.69}\times 100$

$\eta =26.03 %$

b) Work done by the engine

$W = Q_H- Q_C$

$W =1.69 - 1.25$

$W = 0.44\ kJ$

c) Power output

t = 0.296 s

$P = \dfrac{W}{t}$

$P = \dfrac{0.44}{0.296}$

$P = 1.486\ kW$

8 0

3 years ago

What would you say to a friend who made this statement, “The visible-light spectrum of the Sun shows weak hydrogen lines and str

Oliga [24]

Explanation:

spectral lines or signatures of elements depend on temperature, the temperature of the sun is about 5800 K.

at this temperature most calcium atoms are excited to higher energy states than hydrogen atoms and this means that calcium atoms are gonna have more signatures than the atoms of hydrogen.

the statement that the sun shows weak hyrogen lines and strong calcium line is wrong because at the sun's temperature most of the hydrogen atoms are in lower energy states while calcium atoms are in higher energy states hence calcium has more or ''strong'' lines than hydrogen.

8 0

3 years ago

What is the anion of the ionic compound NaC2H3O2<br><br> thank you!

KIM [24]

C₂H₃O₂⁻ is an anion.

<u>Explanation:</u>

NaC₂H₃O₂(s) → Na⁺(aq) + C₂H₃O₂⁻(aq)

NaC₂H₃O₂ when dissociated, yields Na⁺ and C₂H₃O₂⁻.

Anion is a negatively charged ion.

In this case, C₂H₃O₂⁻ is an anion.

6 0

3 years ago

A rock is thrown upward from the level ground in such a way that the maximum height of its flight is equal to its horizontal ran

marshall27 [118]

Answer

a) For the rock

$\dfrac{v_t^2sin 2\theta}{g} = \dfrac{v_t^2sin^2\theta}{2g}$

$2sin\thetacos\theta = \dfrac{sin^2\theta}{2}$

$2cos\theta = \dfrac{sin\theta}{2}$

$tan\theta = 4$

$\theta = tan^{-1} 4$

$\theta = 76^0$

b) $\theta = 45^0$ for maximum range

$\dfrac{d_{max}}{d}=\dfrac{(v_tcos 45^0)(2v_tsin 45^0)g}{(v_tcos 76^0)(2v_tsin 76^0)g}$

$\dfrac{d_{max}}{d}=\dfrac{0.707\times 0.707)}{0.97\times 0.242}$

$\dfrac{d_{max}}{d}=2.129$

$d_{max}=2.129 d$

c) The value of θ is the same on every planet as g divides out.

5 0

3 years ago

Why is density used to determine the identity of matter?

dedylja [7]

a substance's density is the same at a certain pressure and temperature, and the density of one substance is usually different than another substance.

4 0

2 years ago