Final answer:
The velocity function is v(t) = 4t^3 - 196t. The velocity after 3 seconds is -540 ft/s.
Step-by-step explanation:
The velocity of a particle is given by the derivative of the position function. So, to find the velocity function, we need to find the derivative of the given function s(t) = t^4 - 98t^2 + 2401.
Taking the derivative, we get v(t) = 4t^3 - 196t.
(B) To find the velocity after 3 seconds, substitute t = 3 into the velocity function: v(3) = 4(3)^3 - 196(3) = -540 ft/s.