Answer:
e_12=1-Tc/Th
This is same as the original Carnot engine.
Explanation:
For original Carnot engine, its efficiency is given by
e = 1-Tc/Th
For the composite engine, its efficiency is given by
e_12=(W_1+W_2)/Q_H1
where Q_H1 is the heat input to the first engine, W_1 s the work done by the first engine and W_2 is the work done by the second engine.
But the work done can be written as
W= Q_H + Q_C with Q_H as the heat input and Q_C as the heat emitted to the cold reservoir. So.
e_12=(Q_H1+Q_C1+Q_H2+Q_C2)/Q_H1
But Q_H2 = -Q_C1 so the second and third terms in the numerator cancel
each other.
e_12=1+Q_C2/Q_H1
but, Q_C2/Q_H2= -T_C/T'
⇒ Q_C2 = -Q_H2(T_C/T')
= Q_C1(T_C/T')
(T1 is the intermediate temperature)
But, Q_C1 = -Q_H1(T'/T_H)
so, Q_C2 = -Q_H1(T'/T_H)(T_C/T') = Q_H1(T_C/T_H) So the efficiency of the composite engine is given by
e_12=1-Tc/Th
This is same as the original Carnot engine.
Explanation:
|F|= B/2
B/2 = √(A²+B²+2ABcosθ) ------(1)
Since the resultant of A and B is perpendicular to Vector A
tan90°= BSinθ/(A+BCosθ)
(A+BCosθ)=0
Cosθ=-A/B ----(2)
Using equation (1)
B/2 = √(A²+B²+2ABcosθ)
B/2 = √(A²+B²+2AB×-A/B)
B/2=√(A²+B²-2A²)
B/2=√(B²-A²)
B²/4=B²-A²
A²=B²-B²/4
A²=3B²/4
A=√3B/2
Using equation (2)
Cosθ=-A/B
Cosθ=-[√3B/2]/B
Cosθ=-√3/2
θ= cos^-1 (-√3/2)
θ= 150°
<h3>Answer</h3>
C
The object is at rest or is traveling at constant velocity.
<h3>Explanation</h3>
Acceleration is rate of change of velocity and velocity is a vector quantity which means that it is speed with direction.
If acceleration is zero it means that velocity is constant.
Constant velocity may include zero velocity or "at rest"
and
Speed is zero or speed is constant and no change in direction
This is because of scintillation Twinklin as the light passes through the atmosphere of the Earth. As the air moves in and out, the starlight is refracted, often different colors<span> in </span>different<span> directions. Because of this "chromatic abberation," </span>stars<span>can appear to change </span>colors<span> when they are twinkling strongly</span>
The correct answer for velocity if acceleration is opposite is:
* An initial velocity that is faster than a final velocity
The given parameters are acceleration and initial velocity, it is asked to find the final speed of the body
In kinematics, position, velocity, and acceleration are quantities that are related.
The magnitude and direction of the acceleration are given by the resultant force on the body, in many cases the resultant force is constant in various time intervals, therefore the is acceleration is constant in these intervals even though it may have a different value in each one.
The velocity of the body is defined by the change in position of the body in the unit of time, in the most common case of a system with constant acceleration the velocity is given by
= v₀ + a t
where v₀ and 
are the initial and final velocities of the body, a is the acceleration and t is a time scalar: the bold letters indicate vectors.
If the velocity has a direction and the acceleration is contrary to the equation, we can see that the final velocity must decrease as time advances. Therefore the correct statement is: O An initial velocity that is faster than a final velocity.
Learn more here: brainly.com/question/2136991
