60.
Pt.m2:Vectorial:T+N2+G2+Ff2=m2a
Scalar:Ox:m2gsinβ-T-Ff2=m2a
Oy:N2-m2gcosβ=0=>N2=m2gcosβ
Ff2=μ2N2=μ2m2gcosβ
m2gsinβ-T-μ2m2gcosβ=m2a (1)
Pt.m1: Vectorial: T+N1+G1+Ff1=m1a
Scalar: Ox:T-Ff1-m1gsinα=m1a
Oy:N1-m1gcosα=0=>N1=m1gcosα
Ff1=μ1N1=μ1m1gcosα
T-μ1m1gcosα-m1gsinα=m1a (2)
(1)+(2)=>m2g(sinβ-μ2cosβ)-m1g(sinα+μ1cosα)=(m1+m2)a=>a=g[m2(sinβ-μ2cosβ)-m1(sinα+μ1cosα)]/(m1+m2)
T=m1(a+gsinα+μ1gcosα)
Vectorial:T1+T2+R=0=>R=-(T1+T2);T1⊥T2=>R²=T1²+T2²=2T²
Scalar:R=T√2
61.
Pt.m3:Vectorial:f+G3+N3+Ff3=m3a
Scalar:f-μm3g=m3a (1)
Pt.m1:F+G1+N1+Ff1+T=m1a
Scalar:F-T-μm1g=m1a (2)
Pt.m2:Vectorial:T+G2+N2+Ff2+f=m2a
Scalar:T-μm2g-f=m2a (3)
(1)+(2)+(3)=>F-μ(m1+m2+m3)=(m1+m2+m3)a=>a=-μg+F/(m1+m2+m3)
T=F-m1(a+μg)=F(m2+m3)/(m1+m2+m3)
f=m3(a+μg)
Am facut ultimele doua probleme , calculele le faci tu!
