SlideShare a Scribd company logo
Week 77 (3/1/04)
Relativistic momentum paradox
Two equal masses are connected by a massless string with tension T. (By “massless”,
we mean that it has no mass in its unstretched, zero-length state.) The masses
are constrained to move with speed v along parallel lines, as shown below. The
constraints are then removed, and the masses are drawn together. They collide and
make one blob which continues to move to the right. Is the following reasoning
correct? If your answer is “no”, then state what is invalid about whichever of the
four sentences is/are invalid.
“The forces on the masses point in the y-direction. Therefore, there is no change
in momentum in the x-direction. But the mass of the resulting blob is greater than
the sum of the initial masses (because they collided with some relative speed).
Therefore, the speed of the resulting blob must be less than v (to keep px constant),
so the whole apparatus slows down in the x-direction.”
v
v
T

More Related Content

What's hot

3
33
Engineering Mechanice Lecture 05
Engineering Mechanice Lecture 05Engineering Mechanice Lecture 05
Engineering Mechanice Lecture 05
Self-employed
 
Suci ayu andari ppt
Suci ayu andari pptSuci ayu andari ppt
Suci ayu andari ppt
suciayuandari
 
2nd codition of equilibrium
2nd codition of equilibrium2nd codition of equilibrium
2nd codition of equilibrium
Nestor Enriquez
 
Lecture 4 equilibrium_of_forces
Lecture 4 equilibrium_of_forcesLecture 4 equilibrium_of_forces
Lecture 4 equilibrium_of_forces
Khairul Azhar
 
trasformations
trasformationstrasformations
trasformations
Lucia Andreani
 
Understanding the radial tangential coordinate system
Understanding the radial tangential coordinate systemUnderstanding the radial tangential coordinate system
Understanding the radial tangential coordinate system
Lily Zhang
 
(2) equilibrium
(2) equilibrium(2) equilibrium
(2) equilibrium
physics101
 
Special theory of relativity
Special theory of relativitySpecial theory of relativity
Special theory of relativity
djramrock
 
Presentation1
Presentation1Presentation1
Presentation1
ALFIYA ALSALAM
 
Dinamica ....
Dinamica ....Dinamica ....
Dinamica ....
JosMachado96
 
Momentum
MomentumMomentum
Lo1
Lo1Lo1
Physics Equilibrium
Physics EquilibriumPhysics Equilibrium
Physics Equilibrium
wehaa
 
Lo
LoLo
Definido para fisica
Definido  para fisicaDefinido  para fisica
Definido para fisica
JAYRO14
 
Lecture 4 static_equilibrium
Lecture 4 static_equilibriumLecture 4 static_equilibrium
Lecture 4 static_equilibrium
Khairul Azhar
 
81 einstein’s equivalence principle
81   einstein’s equivalence principle81   einstein’s equivalence principle
81 einstein’s equivalence principle
Miguel Cabral Martín
 
Lecture03
Lecture03Lecture03
Lecture03
nomio0703
 
Scalars and vectors
Scalars and vectorsScalars and vectors
Scalars and vectors
Mandisa Zwane
 

What's hot (20)

3
33
3
 
Engineering Mechanice Lecture 05
Engineering Mechanice Lecture 05Engineering Mechanice Lecture 05
Engineering Mechanice Lecture 05
 
Suci ayu andari ppt
Suci ayu andari pptSuci ayu andari ppt
Suci ayu andari ppt
 
2nd codition of equilibrium
2nd codition of equilibrium2nd codition of equilibrium
2nd codition of equilibrium
 
Lecture 4 equilibrium_of_forces
Lecture 4 equilibrium_of_forcesLecture 4 equilibrium_of_forces
Lecture 4 equilibrium_of_forces
 
trasformations
trasformationstrasformations
trasformations
 
Understanding the radial tangential coordinate system
Understanding the radial tangential coordinate systemUnderstanding the radial tangential coordinate system
Understanding the radial tangential coordinate system
 
(2) equilibrium
(2) equilibrium(2) equilibrium
(2) equilibrium
 
Special theory of relativity
Special theory of relativitySpecial theory of relativity
Special theory of relativity
 
Presentation1
Presentation1Presentation1
Presentation1
 
Dinamica ....
Dinamica ....Dinamica ....
Dinamica ....
 
Momentum
MomentumMomentum
Momentum
 
Lo1
Lo1Lo1
Lo1
 
Physics Equilibrium
Physics EquilibriumPhysics Equilibrium
Physics Equilibrium
 
Lo
LoLo
Lo
 
Definido para fisica
Definido  para fisicaDefinido  para fisica
Definido para fisica
 
Lecture 4 static_equilibrium
Lecture 4 static_equilibriumLecture 4 static_equilibrium
Lecture 4 static_equilibrium
 
81 einstein’s equivalence principle
81   einstein’s equivalence principle81   einstein’s equivalence principle
81 einstein’s equivalence principle
 
Lecture03
Lecture03Lecture03
Lecture03
 
Scalars and vectors
Scalars and vectorsScalars and vectors
Scalars and vectors
 

Similar to Prob77

Vectors and scalars
Vectors and scalarsVectors and scalars
Vectors and scalars
Johnel Esponilla
 
Chapter 2 mechanical equilibrium watson
Chapter 2 mechanical equilibrium watsonChapter 2 mechanical equilibrium watson
Chapter 2 mechanical equilibrium watson
watsonma12
 
Engineering mechanics by A.Vinoth Jebaraj
Engineering mechanics by A.Vinoth JebarajEngineering mechanics by A.Vinoth Jebaraj
Engineering mechanics by A.Vinoth Jebaraj
Vinoth Jebaraj A
 
Forces and Motion (1).pdf
Forces and Motion (1).pdfForces and Motion (1).pdf
Forces and Motion (1).pdf
BalanSK
 
Statics of particle
Statics of particle Statics of particle
Statics of particle
ArundevKozhunthuvel
 
Vectorsandscalars
VectorsandscalarsVectorsandscalars
Vectorsandscalars
Kris Krianne Lionheart
 
Physics
PhysicsPhysics
Physics
knowledge1995
 
Equilibrium and Equation of Equilibrium:2D
Equilibrium and Equation of Equilibrium:2DEquilibrium and Equation of Equilibrium:2D
Equilibrium and Equation of Equilibrium:2D
rasel2211
 
Momento en estructuras
Momento en estructurasMomento en estructuras
Momento en estructuras
Rol D
 
Mechanical Technology Grade 10 Chapter 8 forces
Mechanical Technology Grade 10 Chapter 8 forcesMechanical Technology Grade 10 Chapter 8 forces
Mechanical Technology Grade 10 Chapter 8 forces
Future Managers
 
Statics ppt
Statics pptStatics ppt
Statics ppt
LakshmiPriyaM6
 
How to Prepare Rotational Motion (Physics) for JEE Main
How to Prepare Rotational Motion (Physics) for JEE MainHow to Prepare Rotational Motion (Physics) for JEE Main
How to Prepare Rotational Motion (Physics) for JEE Main
Ednexa
 
Lecture5.pptx
Lecture5.pptxLecture5.pptx
Lecture5.pptx
FatimaMalazai1
 
Unit 1 Notes
Unit 1 NotesUnit 1 Notes
Unit 1 Notes
Bruce Coulter
 
CONSERVATION OF MOMENTUM NameINTWO DIMENSIONS1. Two obje.docx
CONSERVATION OF MOMENTUM NameINTWO DIMENSIONS1. Two obje.docxCONSERVATION OF MOMENTUM NameINTWO DIMENSIONS1. Two obje.docx
CONSERVATION OF MOMENTUM NameINTWO DIMENSIONS1. Two obje.docx
maxinesmith73660
 
Engmech 01 (vectors)
Engmech 01 (vectors)Engmech 01 (vectors)
Engmech 01 (vectors)
physics101
 
Scrodinger Cat, Quantum theory, CP Violation and Anti-matter
Scrodinger Cat, Quantum theory, CP Violation and Anti-matterScrodinger Cat, Quantum theory, CP Violation and Anti-matter
Scrodinger Cat, Quantum theory, CP Violation and Anti-matter
Rubens Zimbres, PhD
 
Engineering mechanics system of coplanar forces by
Engineering mechanics system of coplanar forces by Engineering mechanics system of coplanar forces by
Engineering mechanics system of coplanar forces by
mashnil Gaddapawar
 
Learning object 1 travelling waves
Learning object 1   travelling wavesLearning object 1   travelling waves
Learning object 1 travelling waves
Jodi Wong
 

Similar to Prob77 (19)

Vectors and scalars
Vectors and scalarsVectors and scalars
Vectors and scalars
 
Chapter 2 mechanical equilibrium watson
Chapter 2 mechanical equilibrium watsonChapter 2 mechanical equilibrium watson
Chapter 2 mechanical equilibrium watson
 
Engineering mechanics by A.Vinoth Jebaraj
Engineering mechanics by A.Vinoth JebarajEngineering mechanics by A.Vinoth Jebaraj
Engineering mechanics by A.Vinoth Jebaraj
 
Forces and Motion (1).pdf
Forces and Motion (1).pdfForces and Motion (1).pdf
Forces and Motion (1).pdf
 
Statics of particle
Statics of particle Statics of particle
Statics of particle
 
Vectorsandscalars
VectorsandscalarsVectorsandscalars
Vectorsandscalars
 
Physics
PhysicsPhysics
Physics
 
Equilibrium and Equation of Equilibrium:2D
Equilibrium and Equation of Equilibrium:2DEquilibrium and Equation of Equilibrium:2D
Equilibrium and Equation of Equilibrium:2D
 
Momento en estructuras
Momento en estructurasMomento en estructuras
Momento en estructuras
 
Mechanical Technology Grade 10 Chapter 8 forces
Mechanical Technology Grade 10 Chapter 8 forcesMechanical Technology Grade 10 Chapter 8 forces
Mechanical Technology Grade 10 Chapter 8 forces
 
Statics ppt
Statics pptStatics ppt
Statics ppt
 
How to Prepare Rotational Motion (Physics) for JEE Main
How to Prepare Rotational Motion (Physics) for JEE MainHow to Prepare Rotational Motion (Physics) for JEE Main
How to Prepare Rotational Motion (Physics) for JEE Main
 
Lecture5.pptx
Lecture5.pptxLecture5.pptx
Lecture5.pptx
 
Unit 1 Notes
Unit 1 NotesUnit 1 Notes
Unit 1 Notes
 
CONSERVATION OF MOMENTUM NameINTWO DIMENSIONS1. Two obje.docx
CONSERVATION OF MOMENTUM NameINTWO DIMENSIONS1. Two obje.docxCONSERVATION OF MOMENTUM NameINTWO DIMENSIONS1. Two obje.docx
CONSERVATION OF MOMENTUM NameINTWO DIMENSIONS1. Two obje.docx
 
Engmech 01 (vectors)
Engmech 01 (vectors)Engmech 01 (vectors)
Engmech 01 (vectors)
 
Scrodinger Cat, Quantum theory, CP Violation and Anti-matter
Scrodinger Cat, Quantum theory, CP Violation and Anti-matterScrodinger Cat, Quantum theory, CP Violation and Anti-matter
Scrodinger Cat, Quantum theory, CP Violation and Anti-matter
 
Engineering mechanics system of coplanar forces by
Engineering mechanics system of coplanar forces by Engineering mechanics system of coplanar forces by
Engineering mechanics system of coplanar forces by
 
Learning object 1 travelling waves
Learning object 1   travelling wavesLearning object 1   travelling waves
Learning object 1 travelling waves
 

More from eli priyatna laidan

Up ppg daljab latihan soal-pgsd-set-2
Up ppg daljab latihan soal-pgsd-set-2Up ppg daljab latihan soal-pgsd-set-2
Up ppg daljab latihan soal-pgsd-set-2
eli priyatna laidan
 
Soal utn plus kunci gurusd.net
Soal utn plus kunci gurusd.netSoal utn plus kunci gurusd.net
Soal utn plus kunci gurusd.net
eli priyatna laidan
 
Soal up sosial kepribadian pendidik 5
Soal up sosial kepribadian pendidik 5Soal up sosial kepribadian pendidik 5
Soal up sosial kepribadian pendidik 5
eli priyatna laidan
 
Soal up sosial kepribadian pendidik 4
Soal up sosial kepribadian pendidik 4Soal up sosial kepribadian pendidik 4
Soal up sosial kepribadian pendidik 4
eli priyatna laidan
 
Soal up sosial kepribadian pendidik 3
Soal up sosial kepribadian pendidik 3Soal up sosial kepribadian pendidik 3
Soal up sosial kepribadian pendidik 3
eli priyatna laidan
 
Soal up sosial kepribadian pendidik 2
Soal up sosial kepribadian pendidik 2Soal up sosial kepribadian pendidik 2
Soal up sosial kepribadian pendidik 2
eli priyatna laidan
 
Soal up sosial kepribadian pendidik 1
Soal up sosial kepribadian pendidik 1Soal up sosial kepribadian pendidik 1
Soal up sosial kepribadian pendidik 1
eli priyatna laidan
 
Soal up akmal
Soal up akmalSoal up akmal
Soal up akmal
eli priyatna laidan
 
Soal tkp serta kunci jawabannya
Soal tkp serta kunci jawabannyaSoal tkp serta kunci jawabannya
Soal tkp serta kunci jawabannya
eli priyatna laidan
 
Soal tes wawasan kebangsaan
Soal tes wawasan kebangsaanSoal tes wawasan kebangsaan
Soal tes wawasan kebangsaan
eli priyatna laidan
 
Soal sospri ukm ulang i 2017 1 (1)
Soal sospri ukm ulang i 2017 1 (1)Soal sospri ukm ulang i 2017 1 (1)
Soal sospri ukm ulang i 2017 1 (1)
eli priyatna laidan
 
Soal perkembangan kognitif peserta didik
Soal perkembangan kognitif peserta didikSoal perkembangan kognitif peserta didik
Soal perkembangan kognitif peserta didik
eli priyatna laidan
 
Soal latihan utn pedagogik plpg 2017
Soal latihan utn pedagogik plpg 2017Soal latihan utn pedagogik plpg 2017
Soal latihan utn pedagogik plpg 2017
eli priyatna laidan
 
Rekap soal kompetensi pedagogi
Rekap soal kompetensi pedagogiRekap soal kompetensi pedagogi
Rekap soal kompetensi pedagogi
eli priyatna laidan
 
Bank soal pedagogik terbaru 175 soal-v2
Bank soal pedagogik terbaru 175 soal-v2Bank soal pedagogik terbaru 175 soal-v2
Bank soal pedagogik terbaru 175 soal-v2
eli priyatna laidan
 
Bank soal ppg
Bank soal ppgBank soal ppg
Bank soal ppg
eli priyatna laidan
 
Soal cpns-paket-17
Soal cpns-paket-17Soal cpns-paket-17
Soal cpns-paket-17
eli priyatna laidan
 
Soal cpns-paket-14
Soal cpns-paket-14Soal cpns-paket-14
Soal cpns-paket-14
eli priyatna laidan
 
Soal cpns-paket-13
Soal cpns-paket-13Soal cpns-paket-13
Soal cpns-paket-13
eli priyatna laidan
 
Soal cpns-paket-12
Soal cpns-paket-12Soal cpns-paket-12
Soal cpns-paket-12
eli priyatna laidan
 

More from eli priyatna laidan (20)

Up ppg daljab latihan soal-pgsd-set-2
Up ppg daljab latihan soal-pgsd-set-2Up ppg daljab latihan soal-pgsd-set-2
Up ppg daljab latihan soal-pgsd-set-2
 
Soal utn plus kunci gurusd.net
Soal utn plus kunci gurusd.netSoal utn plus kunci gurusd.net
Soal utn plus kunci gurusd.net
 
Soal up sosial kepribadian pendidik 5
Soal up sosial kepribadian pendidik 5Soal up sosial kepribadian pendidik 5
Soal up sosial kepribadian pendidik 5
 
Soal up sosial kepribadian pendidik 4
Soal up sosial kepribadian pendidik 4Soal up sosial kepribadian pendidik 4
Soal up sosial kepribadian pendidik 4
 
Soal up sosial kepribadian pendidik 3
Soal up sosial kepribadian pendidik 3Soal up sosial kepribadian pendidik 3
Soal up sosial kepribadian pendidik 3
 
Soal up sosial kepribadian pendidik 2
Soal up sosial kepribadian pendidik 2Soal up sosial kepribadian pendidik 2
Soal up sosial kepribadian pendidik 2
 
Soal up sosial kepribadian pendidik 1
Soal up sosial kepribadian pendidik 1Soal up sosial kepribadian pendidik 1
Soal up sosial kepribadian pendidik 1
 
Soal up akmal
Soal up akmalSoal up akmal
Soal up akmal
 
Soal tkp serta kunci jawabannya
Soal tkp serta kunci jawabannyaSoal tkp serta kunci jawabannya
Soal tkp serta kunci jawabannya
 
Soal tes wawasan kebangsaan
Soal tes wawasan kebangsaanSoal tes wawasan kebangsaan
Soal tes wawasan kebangsaan
 
Soal sospri ukm ulang i 2017 1 (1)
Soal sospri ukm ulang i 2017 1 (1)Soal sospri ukm ulang i 2017 1 (1)
Soal sospri ukm ulang i 2017 1 (1)
 
Soal perkembangan kognitif peserta didik
Soal perkembangan kognitif peserta didikSoal perkembangan kognitif peserta didik
Soal perkembangan kognitif peserta didik
 
Soal latihan utn pedagogik plpg 2017
Soal latihan utn pedagogik plpg 2017Soal latihan utn pedagogik plpg 2017
Soal latihan utn pedagogik plpg 2017
 
Rekap soal kompetensi pedagogi
Rekap soal kompetensi pedagogiRekap soal kompetensi pedagogi
Rekap soal kompetensi pedagogi
 
Bank soal pedagogik terbaru 175 soal-v2
Bank soal pedagogik terbaru 175 soal-v2Bank soal pedagogik terbaru 175 soal-v2
Bank soal pedagogik terbaru 175 soal-v2
 
Bank soal ppg
Bank soal ppgBank soal ppg
Bank soal ppg
 
Soal cpns-paket-17
Soal cpns-paket-17Soal cpns-paket-17
Soal cpns-paket-17
 
Soal cpns-paket-14
Soal cpns-paket-14Soal cpns-paket-14
Soal cpns-paket-14
 
Soal cpns-paket-13
Soal cpns-paket-13Soal cpns-paket-13
Soal cpns-paket-13
 
Soal cpns-paket-12
Soal cpns-paket-12Soal cpns-paket-12
Soal cpns-paket-12
 

Prob77

  • 1. Week 77 (3/1/04) Relativistic momentum paradox Two equal masses are connected by a massless string with tension T. (By “massless”, we mean that it has no mass in its unstretched, zero-length state.) The masses are constrained to move with speed v along parallel lines, as shown below. The constraints are then removed, and the masses are drawn together. They collide and make one blob which continues to move to the right. Is the following reasoning correct? If your answer is “no”, then state what is invalid about whichever of the four sentences is/are invalid. “The forces on the masses point in the y-direction. Therefore, there is no change in momentum in the x-direction. But the mass of the resulting blob is greater than the sum of the initial masses (because they collided with some relative speed). Therefore, the speed of the resulting blob must be less than v (to keep px constant), so the whole apparatus slows down in the x-direction.” v v T