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3 years ago

Why the efficiency of heat engine is always less than 100%

Physics

2 answers:

valina [46]3 years ago

7 0

Answer:

because some waste heat is always produced produced in a heat engine.

Explanation:

the fraction of heat input that is converted to a net work output is a measure of the performance of the heat engine and is called the thermal efficiency.Since the machine does not contain a source of energy ,nor can it store energy ,from this conversation of energy the power output of machine can never be greater than its input,so efficiency can be less than 100%.

lukranit [14]3 years ago

6 0

Explanation:

The efficiency of heat engine is always less than 100% most of the times because of waste energy in form of heat.

Different forms of heating occurs during the working of an engine
As the mechanical workings of the engine sets in motion, heat is generated.
One of the most common type of the heat is the frictional heating.
Therefore, as energy is transformed from one form to another, some are lost as heat.
In this regard, the efficiency of the engine suffers.

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The maximum deformation of the bumper will occur when the car is temporarily at rest after the collision. We can use the work-energy theorem to solve.

Initially, we only have kinetic energy:

$KE = \frac{1}{2}mv^2$

KE = Kinetic Energy (J)
m = mass (1060 kg)
v = velocity (14.6 m/s)

Once the car is at rest and the bumper is deformed to the maximum, we only have spring-potential energy:

$U_s = \frac{1}{2}kx^2$

k = Spring Constant (1.14 × 10⁷ N/m)

x = compressed distance of bumper (? m)

Since energy is conserved:

$E_I = E_f\\\\KE = U_s\\\\\frac{1}{2}mv^2 = \frac{1}{2}kx^2$

We can simplify and solve for 'x'.

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3 years ago

Read 2 more answers

If she can throw each rock with a speed of 7.5 m/s relative to the ground, causing the wagon to move, how many rocks must she th

Stels [109]

Complete question:

A child sits in a wagon with a pile of 0.64-kg rocks. If she can throw each rock with a speed of 7.5 m/s relative to the ground, causing the wagon to move, how many rocks must she throw per minute to maintain a constant average speed against a 3.9-N force of friction

Answer:

The number of rocks per minutes thrown is 49 rocks/min

Explanation:

Given;

mass of the rock, m = 0.64 kg

speed of the rock, v = 7.5 m/s

frictional force, $f_k$ = 3.9 N

For an object to move at a constant speed, the applied force must be equal to the frictional force.

$f_k = N(F_a)\\\\f_k = N(\frac{mv}{t})\\\\f_k = \frac{N}{t} (mv)\\\\\frac{N}{t} = \frac{f_k}{mv}$

where;

$F_a$ is the applied force

N/t is the number of rocks per minutes thrown

Substitute the given parameters;

$\frac{N}{t} = \frac{f_k}{mv}\\\\ \frac{N}{t} = \frac{3.9}{0.64*7.5}\\\\ \frac{N}{t} = 0.8125 \ \frac{rocks}{second} * \frac{60 \ seconds}{1 \ min} = 48.75 \ \frac{rocks}{min} \$

Approximately 49 rocks/min

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3 years ago

Why the efficiency of heat engine is always less than 100%​

Why the efficiency of heat engine is always less than 100%