{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

hw03soln - Phys ic s 1 4 4 Ho w Thing s Wo r k Ho m e wo r...

Info icon This preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Phys ic s 1 4 4 Ho w Thing s Wo rk Home work Se t # 3 Due Monday 3 / 1 / 0 9 In s tru c tio n s You ar e r esponsible for your own homewor k solutions. Consider these pr oblems as pr actice for the exam. Consult me or other students when you have questions, but tr y to wor k the pr oblems by your self as much as you can. Collabor ation is allowed, but you must in d ic ate y o u r c o llab o rato rs , both in the class and outside of it. Fo r e ve ry pro ble m, s h o w all y o u r wo rk . Simply writ ing do wn a final ans we r wit ho ut s ho wing y o ur re as o ning and c alc ulat io ns is unac c e pt able . Draw diag rams and s ke t c he s fo r pro ble ms , whe re us e ful. Fo r any e s s ay t y pe que s t io ns , make s ure t o us e c o mple t e s e nt e nc e s . Pro ble m 1 : Whic h do y o u t hink is mo re impo rt ant , c o ns e rvat io n o f e ne rg y o r c o ns e rvat io n o f mo me nt um? Why do y o u t hink t hat c o ns e rvat io n laws are s o impo rt ant t o phy s ic is t s ? Obvio us ly , t his que s t io n has no rig ht o r wro ng ans we r ( we ll, “Who c are s ? ” is pro bably t he wro ng ans we r) – I’m int e re s t e d in y o ur pe rs o nal o pinio n, and why y o u have t his o pinio n. A g o o d ans we r will dis c us s t he re as o ns and fe e ling s whic h pro mpt y o u t o ans we r t he way y o u do . A var iety of r esponses wer e possible her e. It looked like most people “ voted” for conser vation of ener gy over conser vation of momentum. An impor tant distinction is that ener gy and momentum ar e NOT at all the same thing. So conser vation of momentum is not j ust a differ ent for m of conser vation of ener gy. Additionally, both can be used to make pr edictions. Pro ble m 2 : a) Chapt e r 2 , Exe rc is e 2 2 ( p. 7 9 ) : A ho rs e do e s wo rk o n a c art it ’s pulling alo ng a s t raig ht , le ve l ro ad at a c o ns t ant s pe e d. The ho rs e is t rans fe rring e ne rg y t o t he c art , s o why do e s n’t t he c art g o fas t e r and fas t e r? Whe re is t he e ne rg y g o ing ? Clear ly, fr iction is impor tant. So the fr iction for ce acts opposite the dir ection of motion, and the for war d for ce of the hor se and backwar d for ce of fr iction must add up to a net for ce of zer o so that the velocity r emains constant. Fur ther , the fr iction does negative wor k on the system, tr ansfor ming the ener gy tr ansfer fr om the hor se into the car t into ther mal ener gy ( mostly, along with other kinds of ener gy: sound, defor mation, etc.) instead of kinetic ener gy.
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern