What is the name of this specific silicon isotope

Atortoise and hare start from rest and have a race. as the race begins, both accelerate forward. the hare accelerates uniformly at a rate of 1.3 m/s2 for 4.5 seconds. it then continues at a constant speed for 12.5 seconds, before getting tired and slowing down with constant acceleration coming to rest 99 meters from where it started. the tortoise accelerates uniformly for the entire distance, finally catching the hare just as the hare comes to a stop. 1) how fast is the hare going 1.8 seconds after it starts? see solution 2.34 m/s your submissions: 2.34 computed value: 2.34submitted: saturday, january 19 at 3: 34 pm feedback: correct! 2) how fast is the hare going 9.1 seconds after it starts? see solution 5.85 m/s your submissions: 5.85 computed value: 5.85submitted: saturday, january 19 at 3: 35 pm feedback: correct! 3) how far does the hare travel before it begins to slow down? see solution 86.29 m your submissions: 86.29 computed value: 86.29submitted: saturday, january 19 at 3: 46 pm feedback: correct! 4) what is the acceleration of the hare once it begins to slow down? see solution -1.34 m/s2 your submissions: -1.34 computed value: -1.34submitted: saturday, january 19 at 3: 47 pm feedback: correct! 5) what is the total time the hare is moving? see solution 21.37 s your submissions: 21.37 computed value: 21.37submitted: saturday, january 19 at 3: 49 pm feedback: correct! 6) what is the acceleration of the tortoise?