A projectile is fired with a horizontal velocity 330m/s from the top of a cliff 80m. How long will it take to strike the ground at the base of the cliff?

we know that

along the y-direction

s = y = u_yt + (1/2)a_yt²

here

y = 80 m

 u_y = 0 (the y-direction velocity will be zero, the inital velocity will only be along x-direction.)

a_y = 9.81 m/s²

so, we have

80 = 0 + (1/2)x9.81xt²

or

 t² = 160 / 9.81 = 16.308

thus, the time taken will be

t = 4.038 secs