Two blocks of masses 2.9kg and 3.9 kg are held by string upper and lower and given the acceleration 0.2 in upward direction gind tension

Tension where? above the two blocks?

Tension=(3.9+2.9)(g+a)

between the two blocks
Tension=Lowerblockmass(g+a)

To find the tension in the strings, we need to consider the forces acting on each block separately.

Let's start with the block of mass 2.9 kg. The forces acting on this block are its weight (mg) acting vertically downward and the tension in the upper string (T1) acting vertically upward. Since the block is accelerating upward, the net force acting on the block must be in the upward direction.

Using Newton's second law (F = ma), we can write the equation for the block of mass 2.9 kg as:

T1 - mg = ma1 ----(1)

Here, m is the mass of the block (2.9 kg), a1 is the acceleration of the block (0.2 m/s^2), and g is the acceleration due to gravity (9.8 m/s^2).

Similarly, for the block of mass 3.9 kg, the forces acting on it are its weight (mg) acting vertically downward, the tension in the upper string (T1) acting vertically upward, and the tension in the lower string (T2) acting vertically upward. Since the block is accelerating upward, the net force acting on the block must be in the upward direction.

So, we can write the equation for the block of mass 3.9 kg as:

T1 + T2 - mg = ma2 ----(2)

Here, m is the mass of the block (3.9 kg), a2 is the acceleration of the block (0.2 m/s^2), and g is the acceleration due to gravity (9.8 m/s^2).

Now, we have two equations with two unknowns (T1 and T2). We can solve these equations simultaneously to find the values of T1 and T2.

Simplifying equation (1), we get:

T1 = mg + ma1 ----(3)

Substituting the values, we have:

T1 = (2.9 kg)(9.8 m/s^2) + (2.9 kg)(0.2 m/s^2)
T1 = 28.42 N

Now, substituting the value of T1 in equation (2), we have:

(28.42 N) + T2 - (3.9 kg)(9.8 m/s^2) = (3.9 kg)(0.2 m/s^2)

Simplifying further:

T2 = (3.9 kg)(0.2 m/s^2) - (28.42 N) + (3.9 kg)(9.8 m/s^2)
T2 = 7.8 N - 28.42 N + 38.22 N
T2 = 17.6 N

Therefore, the tension in the upper string (T1) is 28.42 N, and the tension in the lower string (T2) is 17.6 N.