Newton's Second Law

Newton's Second Law tells us that the net external force on a body equals the product of its mass and its acceleration, written as $F=ma$. On smooth ice the frictional resistance is negligible, so the striking force is essentially the entire net force responsible for the puck's acceleration. Substituting the given values, $F=0.16\times 25=4\text{ N}$. The value 2 N corresponds to an acceleration of only 12.5 m/s^2, half the stated figure, so it is incorrect. The value 6 N would require an acceleration of 37.5 m/s^2, which exceeds what is given. The value 8 N would correspond to doubling the true mass or acceleration and therefore cannot match the data. This is a direct application of the NCERT formulation of the Second Law for a single body on a frictionless surface. As a unit check, kilogram times metre per second squared yields the newton, and the modest 4 N magnitude is reasonable for a light puck on slippery ice.