1. Mechanics again

S1 and S2 are light inextensible strings, and A and B are particles each of mass 0.2 kg. Particles suspended from a fixed point 0 by the string S1 and particle B is suspended from A by the string. The particle hang in equlibirum...

Find tension in s1 and s2

s1 = 4 N and s2 = 2N

Second part, string S1 is cut and the particles fall, the air resistance acting on A is 0.4N and the air resistance on B is 0.2N

Find acceleration force acting on the particles and tenstion in s2 ???!!

Could someone explain me the concept of this.... exams are close and i dont understand this question at all

2. Originally Posted by ramzel
S1 and S2 are light inextensible strings, and A and B are particles each of mass 0.2 kg. Particles suspended from a fixed point 0 by the string S1 and particle B is suspended from A by the string. The particle hang in equlibirum...

Find tension in s1 and s2

s1 = 4 N and s2 = 2N

Second part, string S1 is cut and the particles fall, the air resistance acting on A is 0.4N and the air resistance on B is 0.2N

Find acceleration force acting on the particles and tenstion in s2 ???!!

Could someone explain me the concept of this.... exams are close and i dont understand this question at all
forces acting on mass A ...

$\displaystyle R_A = 0.4$ N up , $\displaystyle T$ down, $\displaystyle mg$ down

$\displaystyle F_{net} = ma$

$\displaystyle T + mg - R_A = ma$

forces acting on mass B ...

$\displaystyle R_B = 0.2$ N up , $\displaystyle T$ up , $\displaystyle mg$ down

$\displaystyle mg - T - R_B = ma$

combine the two equations ...

$\displaystyle 2mg - R_A - R_B = 2ma$

$\displaystyle a = \frac{2mg - R_A - R_B}{2m}$

sub in your values to find $\displaystyle a$ , then go back to either equation and calculate $\displaystyle T$.