NTA Abhyas JEE Main2020PhysicsRotational MotionPractice
A uniform disc of mass M and radius R is mounted on a fixed horizontal axis. A block of mass m hangs from a massless string that is wrapped around the rim of the disc. The magnitude of the acceleration of the falling block ( m ) is
Options
- A2 M M + 2 m   g
- B2 m M + 2 m   g
- CM + 2 m 2   M     g
- D2 M + m 2 M     g
Correct answer
B. 2 m M + 2 m   g
Step-by-step solution
When pulley has a finite mass M and radius R , then tension in two segments of the string are different. Here, m a = m g - T a = m m + M 2 g = 2 m 2 m + M g