Answer:
12s
Explanation:
the formula is
s = u×t + 0.5×a×t²
where:
s is the displacement of the object at this time (so it's equal to 0)
u is the initial speed
t is the time you have to find
a is the acceleration due to gravity
[tex]0 = 15 \frac{m}{s} \times t + 0.5 \times 2.5 \frac{m}{{s}^{2} } \times {t}^{2} [/tex]
[tex]15 \frac{m}{s} \times t = 0.5 \times 2.5 \frac{m}{ {s}^{2} } \times {t}^{2} [/tex]
[tex]15 \frac{m}{s} = 1.25 \frac{m}{{s}^{2} } \times {t}[/tex]
[tex]t = \frac{15 \frac{m}{ {s}^{} } }{1.25 \frac{m}{ {s}^{2} } } [/tex]
[tex]t = 12s[/tex]
