Two blocks of masses 2 kg and 4 kg 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 of g/2. The tension in the string connected between the blocks will be (Take g = 10m/s2):

Explanation

This is the following solution: Mass(m1) of the first block = 2kg mass(m2) of the second block = 4kg The acceleration of the elevator in an upward direction = g/2 According to Newton's law of motion, The net force on a body = Mass × Acceleration in the body When a body is at rest in an accelerating frame of reference with respect to an observer in the same frame of reference, then the motion of the body is entirely described by using the concept of pseudo-force. Pseudo force on a body = The mass of the body × The accelerating of the observer(in opposite direction) Acceleration due to gravity(g) = 10 ms-2 The pseudo force on the block of mass 2kg for an observer in the elevator is given as; = Mass of the block × Acceleration of the observer in the elevator = 2×g/2 The pseudo force on the block of mass 4kg for an observer in the elevator is given as: =4×g/2 If the acceleration in the blocks is a, then For the block of mass of 4kg; (4kg×g+4kg×g/2)−T=4kg×a 4g+4g/2−T=4a..............(1) For the block of mass 2kg; T−2kg×g/2−2kg×g=2kg×a T−2g/2−2g=2a 2T−2g−4g=4a 2T−6g=4a................(2) From equations (1) and (2), we get 4g+4g/2−T=2T−6g ⇒2T−6g=4g+4g/2−T ⇒4T−12g=8g+4g−2T ⇒6T=24g ⇒T=4g ⇒T=4×10ms−2 ⇒T=40N