AP EAMCET201921 Apr 2019Morning ShiftPhysicsRotational MotionActual
A flywheel of mass 1 ~kg and radius vector (2 i + j +2 k ) m is at rest. When a force (3 i +2 j -4 k ) N acts on it tangentially, it can rotate freely. Then, its angular velocity after 4.5 ~s is
Options
- A2 9 261 rad s ⁻¹
- B3 2 261 rad s ⁻¹
- C261 rad s ⁻¹
- D5 9 261 rad s ⁻¹
Correct answer
C. 261 rad s ⁻¹
Step-by-step solution
Given, mass of flywheel, M=1 ~kg , radius vectors R =(2 i + j +2 k ) m , F =(3 i +2 j -4 k ) N and time, t=4.5 ~s Magnitude of radius (R)= (2)^2+(1)^2+(2)^2 = 9 =3 ~m Similarly, F= 29 ~N Torque on the flywheel, gathered =I =F R= M R^2 2 = 2 F M R = 2 29 1 3 = 2 3 29 gathered Now, the angular velocity, aligned & = ₀+ t =0+ 2 3 29 4.5 ( ₀=0 ) & = 261 rad s ⁻¹ aligned Hence, the correct option is (c).