Circular Motion And Centripetal Force

Referring to NCERT Class 11, Chapter 5 (Laws of Motion), uniform circular motion requires a net inward force called the centripetal force, given by F = mv² / r, directed toward the centre of the circle. This force does not create a new kind of interaction; here it is supplied by the tension in the string. Substituting the given values, F = (0.5 × 4²) / 1 = (0.5 × 16) / 1 = 8 N. Option 4 N forgets to square the speed and uses mv/r. Option 2 N uses only m × v incorrectly without the radius and squaring. Option 16 N omits the mass factor and squares the speed alone. Plausibility check: the force depends on the square of speed, so doubling the speed would quadruple the force; with the given moderate speed and small mass, a value of a few newtons like 8 N is reasonable, and the unit kg·m²/s² ÷ m reduces to newtons, confirming correctness.