i am stuck on the follwing question i have done part (i) but kind of stuck on part (ii). im not sure i think you sub in the value of t=3 seconds into the the answer of part one then use speed= distance/time to get the velocity.
A particle is moving in a straight line. After t seconds its
displacement s metres from a fixed point is given by
(i) Find ds/dt
(ii) Hence find the velocity of the particle 3 seconds
after the start.
(iii) Find the values of t when the particle is stationary.