Answer:
8 m/s^2
Step-by-step explanation:
You can use the equation a = v^2 / r
That is acceleration is equal to velocity squared divided by the radius which in this problem is the length of the string. The velocity is 4m/s and the r the radius is 2 m. Now you can square 4 m/s to get 16 m^2/s^2 THEN you divide by 2 m and the m^2 turns to just m and the 16 to an 8. So, that leaves you with acceleration or in this case centripetal acceleration equals 8 m/s^2.
a = 8 m/s^2 or 8 meters per second squared.