Question

it a ball thrown vertically up attains a maimum height of 80 m, its initial speed is (g= 10ms^-2)
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Answer 1

v = 0

s = 80m

a = -10m/s^2

${v}^{2} - {u}^{2} = 2as$

$0 - {u}^{2} = - 2 \times 10 \times 80$

${u}^{2} = 1600$

$u = 40m {s}^{ - 1}$

Hope it helps