Question

a ball is thrown vertically upwards, it reaches its maximum height in 2.5 s. If the acceleration of the ball 10m/s2 be directed towards the ground. find the initial velocity

Answer 1

we know that a=v-u/t
now we know that when any object is thrown upwards its final velocity becomes 0
so
a=10
v=0
t=2.5
u=?
10=0-u/2.5
u=-25m/s

Answer 2

v=0
t=2.5 sec
a= -10m/s2
u=?
v=u+at
0=u+(-10×2.5)
u=25m/s