1. Differentiate the displacement equation (s) to get the velocity equation (v).
2. Use the velocity equation found in (1). Substitute t=0 and the A value found in (1). The reason we substitute t=0 is because the question wants us to find initial velocity or the velocity when the timer started counting.
3. When the particle first comes to instantaneous rest, equate the velocity equation to 0, find for t. There are a few answers for t, take the first answer. Substitute the answer into the displacement equation to find the displacement when v=0 for the first time. Please check if the initial displacement is 0 i.e. s=0 when t=0. If you do not check, you will get the wrong distance. For this question when we substitute t=0 into the displacement equation (s) we got s = 6.9282 m. In this case, you will need to add 6.9282m to the displacement of s=-8m when t=2.5s to get the distance.

Additional Math (A-Math)  amath Small Group Tuition. for a-amath students living in Woodlands, Choa Chu Kang, Yew Tee, Yishun and Sembawang