A ball is thrown vertically downwards with initial velocity 5 m.s from 30 m above the ground. how long does it take for the ball to hit the ground? g=10 m/s

Question

abhisar · Answer

Here,
initial velocity = 5 m/s
Distance = 30 m
Acceleration = 10 m/s^2

We need to find time taken, we can use the equation $\sf s=ut+0.5at^2$

$\Rightarrow \sf 30=5\times t + 0.5\times 10\times t^2\ \Rightarrow 5t^2+5t-30=0$

abhisar · Answer

ok ?

abhisar · Answer

Now solving the quadratic equation, we get values of t as -3 and 2

anonymous · Answer

Okay got it, what formula is this? I'm not quite sure with this formula.

abhisar · Answer

Since time can not be negative, we take t as 2

abhisar · Answer

$\boxed{\sf \huge s=ut+\frac{1}{2}at^2}$

anonymous · Answer

I see thanks!

abhisar · Answer

My pleasure :)