###### Asked in Physics

Physics

# What is the efficiency of a street cleaner's engine when the heat input is 200000 joules and the heat waste is 150000 joules?

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## Related Questions

###### Asked in Physics, Chemistry, Energy

### What is the efficiency of a cars engine when heat input is 200000 joules and the waste heat is 150000 joules?

If the waste heat is 15 compared to the total heat input of 20
(ignoring the thousands) this means the heat doing useful work is
5, which represents 25 percent of the total input heat, so this is
the efficiency. Waste heat in a car is the sum of the engine
cooling losses and the exhaust losses, the rest is converted to
mechanical energy which is useful.
25%

###### Asked in Physics, Energy

### Machine that transforms heat into mechanical energy?

A ficticious heat engine that works at the maximum theoretical
efficiency is called a Carnot engine. Real engines, that obviously
work at a lesser efficiency, include the combustion engines found
in cars.
A ficticious heat engine that works at the maximum theoretical
efficiency is called a Carnot engine. Real engines, that obviously
work at a lesser efficiency, include the combustion engines found
in cars.
A ficticious heat engine that works at the maximum theoretical
efficiency is called a Carnot engine. Real engines, that obviously
work at a lesser efficiency, include the combustion engines found
in cars.
A ficticious heat engine that works at the maximum theoretical
efficiency is called a Carnot engine. Real engines, that obviously
work at a lesser efficiency, include the combustion engines found
in cars.

###### Asked in Mechanics

### What is the efficiency of an engine when the heat input is 200000 joules and the waste heat is 150000joules?

Out of the 200KJ input, 150KJ isn't usable. The only usable
output of the
machine is the remaining 50KJ.
The efficiency of that machine is 50KJ/200KJ =
25% .
It must be pointed out, though, that it all depends on your
definition of what is
usable and non-usable output. For example, if this machine were
labeled as an
"Office Space Heater", then the 150KJ of heat would be the
usable output, and
the efficiency would have been 75% .

###### Asked in Fuel and Engines

### Why efficiency of carnot heat engine is always greater than that of an actual engine?

The efficiency of a Carnot engine is theoretically always
greater than that of an actual engine. The fact that it is
impossible to build a thermodynamically reversable engine, which is
one of the variables necessary to calculate its superiority to a
real heat engine, makes the theorum practical for assessing a real
heat engines efficiency only.

###### Asked in Math and Arithmetic

### How do you calculate the efficiency of a machine?

Efficiency is nothing but calculating how the machine is
performing for what it has been made for,
Efficiency is usually calculated in % as (output/input
)X100.
for Eg. the Thermal efficiency of an reciprocating gasoline
engine can be calculated as follows,
Let,
the input for an reciprocating engine is 12MJ and its out put is
4MJ
then Efficiency is (4/12)X100 = 33%

###### Asked in Energy

### Which engine wastes the most energy?

I would say, heat engine on earth would waste the most energy
since it is always limited by thermodynamic efficiency to have some
loss. In general, lower the temperature difference will resulted to
lower the efficiency, a simple steam engine for a train would be of
lower efficiency than a internal combustion engine and lower than
complex high pressure steam turbine and is probably the lowest
engine efficiency in commercial scale.

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