Question

Three equal weights of mass 2 kg each and
hanging on a string passing over a fixer
frictionless pulley. The tension in the string AB​

Answer 1

║⊕ANSWER⊕║

Let us take the tension between A and B be T and tension between B and C be T1.

The masses are connected to a massless string moving over a frictionless pulley.

Now, if they are allowed to move freely, then they move with common magnitude of acceleration 'a'.

Mass of A, B and C = 2kg (m)

Now,

For C,

=> ma = mg - T1

=> T1 = mg - ma. ....(1)

For B,

=> ma = mg + T1 - T. ....(2)

For A,

=> ma = T - mg

=> T = ma + mg. ....(3)

Now, from (1) and (3) we will put value of The and T1 in (2), we get

=> ma = mg + (mg - ma) - (ma + mg)

=> ma = mg + mg - ma - ma - mg

=> 3ma = mg

=> a = g/3

Now, putting the value in (1) and (3), we will get the tensions.

Tension between B and C = m(g - a)

= m(g - g/3)

= 2(2g/3)

= 4g/3. (g = 10)

= 40/3

= 13.3N

Tension between A and B = m(a + g)

= m(g/3 + g)

= 2(4g/3)

= 8g/3

= 80/3

= 26.6N