Two blocks of masses 2kg and 4kg are hanging with the help of a massless string passing over an ideal pulley inside an elevator. The elevator is moving upward with an acceleration g/2. The tension in the string connected between the blocks will be (take g = 10 ms^–2)
a) 40N

b) 60N

c) 80N

d) 20N

Question

Philoid · Accepted Answer

The elevator (lift) is moving up with acceleration:

Two masses are attached to a pulley inside the elevator.

To Find: Tension in the string = T = ?

Let T be the tension in the string. Since our frame of reference is accelerating, hence is non-inertial.

To use Newton’s laws, we have to add a pseudo force m× in doa wnward direction.

In other words net acceleration due to gravity becomes:

Both have same accelthe eration

The equation of motion for are:

...1

...2

Similarly,

...3

Now, putting 2 in 3, we get:

Now,

So,

Two blocks of masses 2kg and 4kg are hanging with the help of a massless string passing over an ideal pulley inside an elevator. The elevator is moving upward with an acceleration g/2. The tension in the string connected between the blocks will be (take g = 10 ms–2)a) 40Nb) 60Nc) 80Nd) 20N