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3 years ago

The laws of thermodynamics state that, in a heat engine, _____.

Physics

2 answers:

Daniel [21]3 years ago

5 0

Answer: The correct option is "all the heat energy from a source cannot be converted to mechanical energy"

Explanation:

Heat engine is a system which converts heat energy to the mechanical energy. During this process, a lot of heat energy is lost to surrounding.

Heat engine is a device that uses heat to do work. It is impossible to extract an amount of heat from the reservoir at high temperature and use this heat to do some work.

Some heat is rejected to the reservoir at low temperature.

Therefore, the laws of thermodynamics state that, in a heat engine, all the heat energy from a source cannot be converted to mechanical energy.

olchik [2.2K]3 years ago

4 0

There are four laws of thermodynamic which define and characterize the thermodynamic system at thermal equilibrium.
The laws of thermodynamics state that, in a heat engine, all the heat energy from a source cannot be converted to mechanical energy.

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A 1400 kg car starts from rest on a horizontal road and gains a speed of 61 km/h in 19 s. (a) what is its kinetic energy at the

lana [24]

(a) Let's convert the final speed of the car in m/s:
$v_f = 61 km/h = 16.9 m/s$
The kinetic energy of the car at t=19 s is
$K= \frac{1}{2}mv_f^2= \frac{1}{2}(1400 kg)(16.9 m/s)^2=2.00 \cdot 10^5 J$

(b) The average power delivered by the engine of the car during the 19 s is equal to the work done by the engine divided by the time interval:
$P= \frac{W}{\Delta t}$
But the work done is equal to the increase in kinetic energy of the car, and since its initial kinetic energy is zero (because the car starts from rest), this translates into
$P= \frac{K}{\Delta t}= \frac{2.00 \cdot 10^5 J}{19 s}=1.05 \cdot 10^4 W$

(c) The instantaneous power is given by
$P_i = Fv_f$
where F is the force exerted by the engine, equal to F=ma.

So we need to find the acceleration first:
$a= \frac{v_f-v_i}{\Delta t}= \frac{16.9 m/s}{19 s}=0.89 m/s^2$
And the problem says this acceleration is constant during the motion, so now we can calculate the instantaneous power at t=19 s:
$P_i = Fv=(ma)v=(1400 kg)(0.89 m/s^2)(16.9 m/s)=2.11 \cdot 10^4 W$

5 0

3 years ago

How do very small objects behave?

nataly862011 [7]

A. very small objects behave like like particles.

7 0

3 years ago

Read 2 more answers

3. is the force on a dropped ball. gravity acceleration

Oduvanchick [21]

Answer:

Speeding up While Falling Down

Gravity is a force that pulls objects down toward the ground. When objects fall to the ground, gravity causes them to accelerate. Acceleration is a change in velocity, and velocity, in turn, is a measure of the speed and direction of motion.

mark me as brainliest

Explanation:

5 0

2 years ago

How much force (in Newtons) acts on a 1700 kg car going around a

Daniel [21]

Answer:

b) 4781 N

Explanation:

Because there is a redius do this question is talking about the acceleration force which= mv^2/r

so a=15^2/80=2.8125 m^2/s

so the force will be = m.a

F =1700×2.8125=4781.25 N

5 0

2 years ago

Calcular la resistencia de una varilla de grafito de 170 cm de longitud y 60 mm2. Resistividad grafito 3,5 10-5 Ωm

ozzi

Answer:

R = 0.992 Ω

Explanation:

En esta pregunta, dada la información que contiene, debemos calcular la resistencia de la varilla de grafito.

Matemáticamente,

Resistencia = (resistividad * longitud) / Área De la pregunta;

Resistividad = 3,5 * 10 ^ -5 Ωm

longitud = 170 cm = 1,7 m

Área = 60 mm ^ 2 = 60/1000000 = 6 * 10 ^ -5 m ^ 2

Conectando estos valores a la ecuación anterior, tenemos;

Resistencia = (3.5 * 10 ^ -5 * 1.7) / (6 * 10 ^ -5) =

(3.5 * 1.7) / 6 = 0.992 Ω

3 0

3 years ago