A stone is projected vertically upwards with a velocity of 12ms'. Calculate or find: a) How long it took the stone to reach its maximum height.

b) Maximum height reached by the stone.

The acceleration of the stone will be -9.8 m/s^2, because of the acceleration of earth's gravity, the initial velocity will be 12 m/s, and the final velocity will be 0 m/s. Therefore, we can solve using a kinematic equation to solve the problems:

a)

Final Velocity = Initial Velocity + Acceleration * Time

0 = 12 + -9.8*t

-12 = -9.8*t

t = 12/9.8 ≈ 1.224

Therefore, the time is equal to 12/9.8 ≈ 1.2245 seconds.

b)

Displacement = (Initial Velocity + Final Velocity)/2 * Time

d = (12+0)/2*1.2245

d = 6*1.2245

d = 7.347

Therefore, the maximum height is approximately equal to 7.347 meters.