A particle in circular motion has a centripetal acceleration of 100m/s2 and speed of 20m/s. What is its radius?
Centripetal acceleration a_c=v²/r=4π²r/T²=4π²rf² per NCERT circular motion. Substituting r and frequency/period gives a_c value matching 4 m. Other options use incorrect r or f, so C is correct.
Ref: NCERT Class 11 Physics > Chapter 4: Motion in a Plane > Topic: Two-Dimensional Motion and Vectors