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Benzinmotor

About points...

We associate a certain number of points with each exercise.
When you click an exercise into a collection, this number will be taken as points for the exercise, kind of "by default".
But once the exercise is on the collection, you can edit the number of points for the exercise in the collection independently, without any effect on "points by default" as represented by the number here.

That being said... How many "default points" should you associate with an exercise upon creation?
As with difficulty, there is no straight forward and generally accepted way.
But as a guideline, we tend to give as many points by default as there are mathematical steps to do in the exercise.
Again, very vague... But the number should kind of represent the "work" required.

About difficulty...

We associate a certain difficulty with each exercise.
When you click an exercise into a collection, this number will be taken as difficulty for the exercise, kind of "by default".
But once the exercise is on the collection, you can edit its difficulty in the collection independently, without any effect on the "difficulty by default" here.
Why we use chess pieces? Well... we like chess, we like playing around with \(\LaTeX\)-fonts, we wanted symbols that need less space than six stars in a table-column... But in your layouts, you are of course free to indicate the difficulty of the exercise the way you want.

That being said... How "difficult" is an exercise? It depends on many factors, like what was being taught etc.
In physics exercises, we try to follow this pattern:

Level 1 - One formula (one you would find in a reference book) is enough to solve the exercise. Example exercise

Level 2 - Two formulas are needed, it's possible to compute an "in-between" solution, i.e. no algebraic equation needed. Example exercise

Level 3 - "Chain-computations" like on level 2, but 3+ calculations. Still, no equations, i.e. you are not forced to solve it in an algebraic manner. Example exercise

Level 4 - Exercise needs to be solved by algebraic equations, not possible to calculate numerical "in-between" results. Example exercise

Level 5 -
Level 6 -

Exercise

https://texercises.com/exercise/benzinmotor-2/

Question

Solution

Short

Video

\(\LaTeX\)

Need help? Yes, please!

The following quantities appear in the problem: Zeit \(t\) / Masse \(m\) / Temperatur \(T\) / Arbeit \(W\) / Energie \(E\) / Leistung \(P\) / Heizwert \(H\) / Wirkungsgrad \(\eta\) /

The following formulas must be used to solve the exercise: \(\eta_{\scriptscriptstyle\rm C} = \dfrac{T_{\scriptscriptstyle\rm W} - T_{\scriptscriptstyle\rm K}}{T_{\scriptscriptstyle\rm W}} \quad \) \(E = m \cdot H \quad \) \(P = \dfrac{E}{t} = \dfrac{W}{t} \quad \)

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In case your browser prevents YouTube embedding: https://youtu.be/9ibLM8YK19c

Exercise:
In einem Verbrennungsmotor entzündet das Benzin-Luft-Gemisch bei degreeCelsius und die Abgase haben eine Temperatur von degreeCelsius. Der Motor erbringt eine Nutzleistung von kW und verbraucht stündlich liter Benzin mit einem Heizwert von gigajoulepercubicmeter. Wie viel Prozent des idealen beträgt der tatsächliche Wirkungsgrad?

Solution:
newqtyTwocelsius solqtyTwTwon+.K newqtyTkocelsius solqtyTkTkon+.K newqtyPnokW newqtyPnPnon eW newqtyto.h newqtyts newqtyVoliter newqtyVVon cubicmeter newqtyHogigajoulepercubicmeter newqtyHHon ejoulepercubicmeter % Geg sscTw Two Tw sscTk Tko Tk Pnutz Pno Pn t to t V Vo V tilde H Ho H % GesAnteiletatext in sipercent % Der bestmögliche Wirkungsgrad dieses Verbrennungsmotors -- es ist eine Wärmekraftmaschine -- ist: solqtyetCfracsscTw-sscTksscTwTwn-Tkn/Twn solqtyetCPetCn*percent sscetaC etCf fracTw-TkTw etC etCPTT. Wenn der Motor stündlich Liter Benzin verbrennt so wird ihm dadurch eine Energie von solqtyQVtilde HVn*HnJ Q Qf VH Q zugeführt was einer zugeführten Leistung von solqtyPzfracQftQn/tnW Pzu fracQt Pzf fracQt Pz entspricht. Der reale Wirkungsgrad ist somit: solqtyetRfracPnutz tVtilde HPnn/Pzn solqtyetRPetRn*percent sscetar fracPnutzPzu fracPnutzPzf etRf fracPnPz etR etRPTT. Das sind solqtyetetRffracsscTwsscTw-sscTketRn/etCn solqtyetPetn*percent eta fracsscetarsscetaC fracetRfetCf etf fracetRetC et etPTT des idealen bestmöglichen Carnot-Wirkungsgrades. % eta etf etPTT

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Contained in these collections:

Wärmearbeitsmaschine 1 by uz

7 | 8
Wärmearbeitsmaschine real vs. ideal by TeXercises

1 | 7
Wärmearbeitsmaschine by pw

5 | 8

Attributes & Decorations

Branches	Work, Energy, Power
Tags	benzin, brennwert, heizwert, leistung, physik, verbrennungsmotor, wirkungsgrad, wärmearbeitsmaschine, wärmekraftmaschine, wärmelehre
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Difficulty	(3, default)
Points	5 (default)
Language	(Deutsch)
Type	Calculative / Quantity
Creator	uz
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