Question

Two masses 40kg and 30kg are connected by a weightless string passing over a frictionless pully as shown in the figure.The tension in the string will be​

Answer 1

see a rough diagram of system of the given masses.

as it is clear that 40kg is higher mass than 30kg so, weight of 40kg is higher than 30kg. it means, 40kg mass moves downward and 30kg moves upward.

Let the acceleration of motion is a.

and tension acting on weightless string is T.

from block of mass 30Kg,

T - m1g = m1a

or, T - 30kg × 10m/s² = 30 kg × a

or, T - 300 = 30a.....(1)

from block of mass 40kg,

m2g - T = m2a

40kg × 10m/s² - T = 40 kg × a

or, 400 - T = 40a......(2)

from equations (1) and (2),

a = 10/7 m/s²

and T = 300 + 30 × 10/7 = 2400/7 N

= 342.85 N

hence, tension in string will be 342.85N

Answer 2

hope it will help you....