Answer:
The maximum height it reaches will be 20 m.
The time taken by it to reach the height will be: t = 2 seconds.
Step-by-step explanation:
We know the equation of the motion under gravity
v² - u² = 2gs
u = initial velocity = 20 m/s
v = final velocity = 0 m/s

so

substituting u = 20 m/s, v = 0 m/s, g = -10 and




m
Therefore, the maximum height it reaches will be 20 m.
We know the equation
u = gt
substitute u = 20, g = 10
20 = 10 × t
t = 20/10
t = 2 seconds
Therefore, the time taken by it to reach the height will be: t = 2 seconds.