lucrul mecanic
TRANSCRIPT
![Page 1: Lucrul mecanic](https://reader034.vdocumente.com/reader034/viewer/2022050615/5571fa6e497959916992349c/html5/thumbnails/1.jpg)
![Page 2: Lucrul mecanic](https://reader034.vdocumente.com/reader034/viewer/2022050615/5571fa6e497959916992349c/html5/thumbnails/2.jpg)
• Ce este lucrul mecanic?• Cum se determina lucrul
mecanic?• In ce se masoara lucrul
mecanic?• Cine a fost Joule?• Cum se reprezinta grafic
lucrul mecanic?
![Page 3: Lucrul mecanic](https://reader034.vdocumente.com/reader034/viewer/2022050615/5571fa6e497959916992349c/html5/thumbnails/3.jpg)
• Este o marime fizica care capata sens atunci cand
asupra unui corp actioneaza o forta, iar corpul se deplaseaza.
Ce este lucrul mecanic?
![Page 4: Lucrul mecanic](https://reader034.vdocumente.com/reader034/viewer/2022050615/5571fa6e497959916992349c/html5/thumbnails/4.jpg)
1. Lucrul mecanic cand directia si sensul fortei coincid cu directia si sensul deplasarii (pozitiv):
F F
Δd
d2d1
L = FΔd deplasarea
forta
![Page 5: Lucrul mecanic](https://reader034.vdocumente.com/reader034/viewer/2022050615/5571fa6e497959916992349c/html5/thumbnails/5.jpg)
Δd d2
d1
2. Lucrul mecanic cand directia fortei si a deplasarii coincid dar au sensuri opuse (negativ):
L = -FΔd deplasarea
forta
![Page 6: Lucrul mecanic](https://reader034.vdocumente.com/reader034/viewer/2022050615/5571fa6e497959916992349c/html5/thumbnails/6.jpg)
Δd
d2d1
F F
3. Lucrul mecanic cand directia fortei formeaza un unghi cu directia deplasarii:
deplasarea fortaL=FΔdcosα
α
![Page 7: Lucrul mecanic](https://reader034.vdocumente.com/reader034/viewer/2022050615/5571fa6e497959916992349c/html5/thumbnails/7.jpg)
4. Lucrul mecanic cand directia fortei este perpendiculara pe directia deplasarii:
G
Δd = 0 (pe directia fortei de greutate)
L = 0 deplasarea
forta
![Page 8: Lucrul mecanic](https://reader034.vdocumente.com/reader034/viewer/2022050615/5571fa6e497959916992349c/html5/thumbnails/8.jpg)
In ce se masoara lucrul mecanic?
Observatie: Alte marimi fizice care se masoara in jouli
sunt: • caldura (energia termica) (Q)• energia electrica (W)• energia mecanica(E) - (cinetica Ec si
potentiala Ep)
<L> SI = N.m = J (JOULE)
![Page 9: Lucrul mecanic](https://reader034.vdocumente.com/reader034/viewer/2022050615/5571fa6e497959916992349c/html5/thumbnails/9.jpg)
JAMES PRESCOTT JOULE (1818 – 1889)
• Fizician englez, a fost elevul lui John Dalton;
• A formulat legea conservarii energiei (1843);
• A studiat motoarele electrice;
• A descoperit Legea lui Joule;• A descoperit efectul Joule-
Thomson
Cine a fost Joule?
![Page 10: Lucrul mecanic](https://reader034.vdocumente.com/reader034/viewer/2022050615/5571fa6e497959916992349c/html5/thumbnails/10.jpg)
F creste
Reprezentarea grafica a lucrului mecanic
F scade.F(N)
Δd(m)0
F = const.
Marimea lucrului mecanic e data chiar de suprafata hasurata!
![Page 11: Lucrul mecanic](https://reader034.vdocumente.com/reader034/viewer/2022050615/5571fa6e497959916992349c/html5/thumbnails/11.jpg)