Mecanica Geral

ula-tema: Estática dos pontos Materiais

Passo 2

Discuta e resolva os problemas 3.1, 3.2, 3.3 e 3.4.

Problema 3.1:

∑Fx=0 ∑Fy=0

-40*cos 60°+F1*cos 37°+F2*cos 30° = 0

-200+0,79*F1+0,86*F2 = 0

F1 = -0,86*F2+200/0,79 400*sen 60°-F1*sen37°-F2*sen 30° = 0

344-0,60*(0,786*F2+200/0,79)-0,5*F2 = 0

344-0,65*F2-151,89-0,5*F2 = 0

F2 = 192,11/1,15

F2 = 167,05 lb

F1 = -0,86*(167,05)+200/0,79

F1 = 435,01 lb

Problema 3.2:

∑Fx=0 ∑Fy=0

-7*cos 37°+Fx*cos Ø = 0

-5,53+Fx*cos Ø = 0

Fx = 5,53/cos Ø 7*sen 37°+Fy*sen Ø = 0

4,2-Fy*sen Ø = 0

Fy = 4,2/sen Ø

Fx = 5,53/cos 12°

Fx = 5,70 KN Fx = 5,53/cos Ø = Fy = 4,2/sen Ø

Tg Ø = 4,2/5,53

Tg Ø = 0,21

Ø = 11,8° ou 12°

Fy = 4,2/sen 12°

Fy = 6 KN

Problema 3.3:

∑Fx=0 ∑Fy=0

300*cos 67°+450*cos 20°-F1x*cos Ø = 0

117+418,5-F1x*cos Ø = 0

F1x = 535,5/cos Ø 300*sen 67°-450*sen 20°-F1y*sen Ø = 0

276-153-F1y*sen Ø = 0

F1y = 123/sen Ø

F1x = 535,5/cos 13°

F1x = 552,06 N F1x = 535,5/cos Ø = F1y = 123/sen Ø

Tg Ø = 123/535,5

Tg Ø = 0,229

Ø = 12,8° ou 13°

F1y = 123/sen 13°

F1y = 559,09 N

Problema 3.4:

∑Fx=0 ∑Fy=0

Fx*cos Ø+2,25*cos 60°-7,5*cos 60°-4,5 = 0

Fx*cos Ø+1,125-3,75-4,5 = 0

Fx = 7,125/cos Ø Fy*sen Ø-2,25*sen 60°-7,5*sen 60° = 0

Fy*sen Ø-1,935-6,45 = 0

Fy = 4,515/sen Ø

Fx = 7,125/cos 32°

Fx = 8,48 KN Fx = 7,125/cos Ø = Fy = 4,515/sen Ø

Tg Ø = 4,515/7,125

Tg Ø = 0,63

Ø = 32,2° ou 32°

Fy = 4,515/sen 32°