Answer:
gs = 0.6 m/s^2
Step-by-step explanation:
Given data:
velocity = 12 m/s
height s = 12t -(1/2) g_s t^2
Given velocity is the derivatives of height
![v(t) = (d)/(dt) s(t)](https://img.qammunity.org/2020/formulas/physics/college/kr64gy8bv773bizu9oooeiu9t52e6lxjr8.png)
![= (d)/(dt)(12t -(1)/(2) g_s t^2)](https://img.qammunity.org/2020/formulas/physics/college/3lwrzhoz5skd97z5ymzmdnyjf89j2pow0a.png)
![= 12 - g_s t](https://img.qammunity.org/2020/formulas/physics/college/qlemr75o4ud4sj2fomt2uv9mdx5qip3jn4.png)
when velocity tend to 0 , maximum height is reached
![v(t) = 12 - g_s t](https://img.qammunity.org/2020/formulas/physics/college/cpw4ghxcezihi00ok3qrn1cfhh9cptydcm.png)
![0 = 12 - g_s t](https://img.qammunity.org/2020/formulas/physics/college/c9pq0bdnx8qg7dpcb67fari5x99so3g6sf.png)
![g_s = (12)/(t)](https://img.qammunity.org/2020/formulas/physics/college/vji9h9suyfkwubs8pkgnncikj9mccxcr9l.png)
at t = 20 sec ball reached the max height, so
![g_s = (12)/(20) = 0.6 m/s^2](https://img.qammunity.org/2020/formulas/physics/college/bjxcr78tbv7aqfepase4ycc28v9gmlcciq.png)