Two spaceships
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.
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 -
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 -
Question
Solution
Short
Video
\(\LaTeX\)
Need help? Yes, please!
The following quantities appear in the problem:
Geschwindigkeit \(v\) /
The following formulas must be used to solve the exercise:
\(u' = \frac{u-v}{1-\frac{uv}{c^2}} \quad \)
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Exercise:
Two spaceships leave Earth in opposite directions each with a speed of .c with respect to Earth. abcliste abc What is the velocity of the first spaceship relative to the second spaceship? abc What is the velocity of spaceship two relative to spaceship one? abcliste
Solution:
center tikzpicture scoperotate scale. %flaps coordinate P at --; drawfillblue!!white - tooutin -. tooutin -. tooutin - -- -; scoperotate around:Pshift-cm-cmyscalexscal drawfillblue!!white - tooutin -. tooutin -. tooutin - -- -; scope %rocket drawfillyellow!!white -- tooutin - tooutin tooutin --; %peak drawfillblue!!white -. tooutin . tooutin tooutin -.; %central flap drawfillblue!!white - tooutin - - tooutin -; %porthole drawcolorgrayultra thickfillwhite!!blue -. circle .cm; %fuel foreach i in ... pgfmathsetmacroxrand*. + *- - . pgfmathsetmacroyrand*. + *.-. pgfmathsetmacroopacValrand*.+ drawcolorred fillred!!yellow xy circle .cm; scope pgftransformxshift filldrawcolorblue fillblue!!white circle .cm; drawcolorgreen!!black-latex --; drawcolorgreen!!black-latex --; nodecolorgreen!!black at .. mathcalS'; pgftransformxshift drawcolorgreen!!black-latex --; drawcolorgreen!!black-latex --; nodecolorgreen!!black at .. mathcalS; drawcolorblulatex .--. noderight u_r' .c; drawcolorblulatex -.---. nodeleft u_l' -.c; drawcolorred-latex -..---. nodeleft v -.c; drawcolorred-latex -.-.---.-. nodeleft u_l -.c; scoperotate scale. %flaps coordinate P at --; drawfillblue!!white - tooutin -. tooutin -. tooutin - -- -; scoperotate around:Pshift-cm-cmyscalexscal drawfillblue!!white - tooutin -. tooutin -. tooutin - -- -; scope %rocket drawfillyellow!!white -- tooutin - tooutin tooutin --; %peak drawfillblue!!white -. tooutin . tooutin tooutin -.; %central flap drawfillblue!!white - tooutin - - tooutin -; %porthole drawcolorgrayultra thickfillwhite!!blue -. circle .cm; %fuel foreach i in ... pgfmathsetmacroxrand*. + *- - . pgfmathsetmacroyrand*. + *.-. pgfmathsetmacroopacValrand*.+ drawcolorred fillred!!yellow xy circle .cm; scope tikzpicture center abcliste abc If we name the Earths frame mathcalS' and the frame of spaceship glqq rightgrqq mathcalS then the relative velocity of mathcalS' earth with respect to mathcalS is v-.c. The speed of spaceship glqq leftgrqq as seen from mathcalS' earth is then u_l'-.c. The speed of spaceship glqq leftgrqq in mathcalS is: u_l fracu_l'+v+fracu_l'vc^ frac-.c + -.c+frac-.c-.cc^ -.c abc Since the problem is symmetric we know that u_x''.c. abcliste
Two spaceships leave Earth in opposite directions each with a speed of .c with respect to Earth. abcliste abc What is the velocity of the first spaceship relative to the second spaceship? abc What is the velocity of spaceship two relative to spaceship one? abcliste
Solution:
center tikzpicture scoperotate scale. %flaps coordinate P at --; drawfillblue!!white - tooutin -. tooutin -. tooutin - -- -; scoperotate around:Pshift-cm-cmyscalexscal drawfillblue!!white - tooutin -. tooutin -. tooutin - -- -; scope %rocket drawfillyellow!!white -- tooutin - tooutin tooutin --; %peak drawfillblue!!white -. tooutin . tooutin tooutin -.; %central flap drawfillblue!!white - tooutin - - tooutin -; %porthole drawcolorgrayultra thickfillwhite!!blue -. circle .cm; %fuel foreach i in ... pgfmathsetmacroxrand*. + *- - . pgfmathsetmacroyrand*. + *.-. pgfmathsetmacroopacValrand*.+ drawcolorred fillred!!yellow xy circle .cm; scope pgftransformxshift filldrawcolorblue fillblue!!white circle .cm; drawcolorgreen!!black-latex --; drawcolorgreen!!black-latex --; nodecolorgreen!!black at .. mathcalS'; pgftransformxshift drawcolorgreen!!black-latex --; drawcolorgreen!!black-latex --; nodecolorgreen!!black at .. mathcalS; drawcolorblulatex .--. noderight u_r' .c; drawcolorblulatex -.---. nodeleft u_l' -.c; drawcolorred-latex -..---. nodeleft v -.c; drawcolorred-latex -.-.---.-. nodeleft u_l -.c; scoperotate scale. %flaps coordinate P at --; drawfillblue!!white - tooutin -. tooutin -. tooutin - -- -; scoperotate around:Pshift-cm-cmyscalexscal drawfillblue!!white - tooutin -. tooutin -. tooutin - -- -; scope %rocket drawfillyellow!!white -- tooutin - tooutin tooutin --; %peak drawfillblue!!white -. tooutin . tooutin tooutin -.; %central flap drawfillblue!!white - tooutin - - tooutin -; %porthole drawcolorgrayultra thickfillwhite!!blue -. circle .cm; %fuel foreach i in ... pgfmathsetmacroxrand*. + *- - . pgfmathsetmacroyrand*. + *.-. pgfmathsetmacroopacValrand*.+ drawcolorred fillred!!yellow xy circle .cm; scope tikzpicture center abcliste abc If we name the Earths frame mathcalS' and the frame of spaceship glqq rightgrqq mathcalS then the relative velocity of mathcalS' earth with respect to mathcalS is v-.c. The speed of spaceship glqq leftgrqq as seen from mathcalS' earth is then u_l'-.c. The speed of spaceship glqq leftgrqq in mathcalS is: u_l fracu_l'+v+fracu_l'vc^ frac-.c + -.c+frac-.c-.cc^ -.c abc Since the problem is symmetric we know that u_x''.c. abcliste
Meta Information
Exercise:
Two spaceships leave Earth in opposite directions each with a speed of .c with respect to Earth. abcliste abc What is the velocity of the first spaceship relative to the second spaceship? abc What is the velocity of spaceship two relative to spaceship one? abcliste
Solution:
center tikzpicture scoperotate scale. %flaps coordinate P at --; drawfillblue!!white - tooutin -. tooutin -. tooutin - -- -; scoperotate around:Pshift-cm-cmyscalexscal drawfillblue!!white - tooutin -. tooutin -. tooutin - -- -; scope %rocket drawfillyellow!!white -- tooutin - tooutin tooutin --; %peak drawfillblue!!white -. tooutin . tooutin tooutin -.; %central flap drawfillblue!!white - tooutin - - tooutin -; %porthole drawcolorgrayultra thickfillwhite!!blue -. circle .cm; %fuel foreach i in ... pgfmathsetmacroxrand*. + *- - . pgfmathsetmacroyrand*. + *.-. pgfmathsetmacroopacValrand*.+ drawcolorred fillred!!yellow xy circle .cm; scope pgftransformxshift filldrawcolorblue fillblue!!white circle .cm; drawcolorgreen!!black-latex --; drawcolorgreen!!black-latex --; nodecolorgreen!!black at .. mathcalS'; pgftransformxshift drawcolorgreen!!black-latex --; drawcolorgreen!!black-latex --; nodecolorgreen!!black at .. mathcalS; drawcolorblulatex .--. noderight u_r' .c; drawcolorblulatex -.---. nodeleft u_l' -.c; drawcolorred-latex -..---. nodeleft v -.c; drawcolorred-latex -.-.---.-. nodeleft u_l -.c; scoperotate scale. %flaps coordinate P at --; drawfillblue!!white - tooutin -. tooutin -. tooutin - -- -; scoperotate around:Pshift-cm-cmyscalexscal drawfillblue!!white - tooutin -. tooutin -. tooutin - -- -; scope %rocket drawfillyellow!!white -- tooutin - tooutin tooutin --; %peak drawfillblue!!white -. tooutin . tooutin tooutin -.; %central flap drawfillblue!!white - tooutin - - tooutin -; %porthole drawcolorgrayultra thickfillwhite!!blue -. circle .cm; %fuel foreach i in ... pgfmathsetmacroxrand*. + *- - . pgfmathsetmacroyrand*. + *.-. pgfmathsetmacroopacValrand*.+ drawcolorred fillred!!yellow xy circle .cm; scope tikzpicture center abcliste abc If we name the Earths frame mathcalS' and the frame of spaceship glqq rightgrqq mathcalS then the relative velocity of mathcalS' earth with respect to mathcalS is v-.c. The speed of spaceship glqq leftgrqq as seen from mathcalS' earth is then u_l'-.c. The speed of spaceship glqq leftgrqq in mathcalS is: u_l fracu_l'+v+fracu_l'vc^ frac-.c + -.c+frac-.c-.cc^ -.c abc Since the problem is symmetric we know that u_x''.c. abcliste
Two spaceships leave Earth in opposite directions each with a speed of .c with respect to Earth. abcliste abc What is the velocity of the first spaceship relative to the second spaceship? abc What is the velocity of spaceship two relative to spaceship one? abcliste
Solution:
center tikzpicture scoperotate scale. %flaps coordinate P at --; drawfillblue!!white - tooutin -. tooutin -. tooutin - -- -; scoperotate around:Pshift-cm-cmyscalexscal drawfillblue!!white - tooutin -. tooutin -. tooutin - -- -; scope %rocket drawfillyellow!!white -- tooutin - tooutin tooutin --; %peak drawfillblue!!white -. tooutin . tooutin tooutin -.; %central flap drawfillblue!!white - tooutin - - tooutin -; %porthole drawcolorgrayultra thickfillwhite!!blue -. circle .cm; %fuel foreach i in ... pgfmathsetmacroxrand*. + *- - . pgfmathsetmacroyrand*. + *.-. pgfmathsetmacroopacValrand*.+ drawcolorred fillred!!yellow xy circle .cm; scope pgftransformxshift filldrawcolorblue fillblue!!white circle .cm; drawcolorgreen!!black-latex --; drawcolorgreen!!black-latex --; nodecolorgreen!!black at .. mathcalS'; pgftransformxshift drawcolorgreen!!black-latex --; drawcolorgreen!!black-latex --; nodecolorgreen!!black at .. mathcalS; drawcolorblulatex .--. noderight u_r' .c; drawcolorblulatex -.---. nodeleft u_l' -.c; drawcolorred-latex -..---. nodeleft v -.c; drawcolorred-latex -.-.---.-. nodeleft u_l -.c; scoperotate scale. %flaps coordinate P at --; drawfillblue!!white - tooutin -. tooutin -. tooutin - -- -; scoperotate around:Pshift-cm-cmyscalexscal drawfillblue!!white - tooutin -. tooutin -. tooutin - -- -; scope %rocket drawfillyellow!!white -- tooutin - tooutin tooutin --; %peak drawfillblue!!white -. tooutin . tooutin tooutin -.; %central flap drawfillblue!!white - tooutin - - tooutin -; %porthole drawcolorgrayultra thickfillwhite!!blue -. circle .cm; %fuel foreach i in ... pgfmathsetmacroxrand*. + *- - . pgfmathsetmacroyrand*. + *.-. pgfmathsetmacroopacValrand*.+ drawcolorred fillred!!yellow xy circle .cm; scope tikzpicture center abcliste abc If we name the Earths frame mathcalS' and the frame of spaceship glqq rightgrqq mathcalS then the relative velocity of mathcalS' earth with respect to mathcalS is v-.c. The speed of spaceship glqq leftgrqq as seen from mathcalS' earth is then u_l'-.c. The speed of spaceship glqq leftgrqq in mathcalS is: u_l fracu_l'+v+fracu_l'vc^ frac-.c + -.c+frac-.c-.cc^ -.c abc Since the problem is symmetric we know that u_x''.c. abcliste
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