NEET2018PhysicsRotational MotionActual
A solid sphere is in rolling motion. In rolling motion a body possesses translational kinetic energy K t as well as rotational kinetic energy K r simultaneously. The ratio K t : K t + K r for the sphere is
Options
- A10 : 7
- B5 : 7
- C7 : 10
- D2 : 5
Correct answer
B. 5 : 7
Step-by-step solution
Transnational K E = 1 2 m v 2 Translational K E + Rotational K E = 1 2 m v 2 + 1 2 I ω 2 = 1 2 m v 2 + 1 2 ( 2 5 m r 2 ) ω 2 ∵ for rolling motion v = r ω = 1 2 m v 2 + 1 2 × 2 5 m r 2 ( v r ) 2 = 7 10 m v 2 So, K t K t + K r = 1 2 m v 2 7 10 m v 2 = 5 7