Question

Irrelevant answers and answers without correct explanation will b reported...​

Answer 1

Assume the ball to start  from last stair and it falls down as given in the attachment

Let there be n stairs and the ball hit the stair at no. p

the trajectory formed represent a projectile

then the range can be given as

$R=p\times0.2m\\R=0.2p$

also height can also be calculated

$H=P\times0.2\\H=0.2p$

so now we know that for a PROJECTILE

range and height relation is given as

$R=u\sqrt{\frac{2H}{g} } \\R^{2}=u\times \frac{2\times H}{g} \\(0.2p)^{2}=u\times \frac{2\times 0.2p}{10}\\ 0.04p^{2}=1.8\times \frac{0.4p}{10}\\ 0.04p^{2}=\frac{18\times 0.4p}{10\times 10} \\4p^{2}=18\times 0.4p\\p=\frac{18\times 0.4 p}{4p} \\p \approx 1.8 (as\: we\: assumed \:g=9.8m/s^{2}$

i.e , ball hit 1st step but nearly at it's base or we nearly hit 1st step at the edge

let me know if it's correct

Answer 2

Here you go mate.

Please say if you didn't understand it.

Thanks.

Also... can you please show me the electrostatics question's options, so that I can verify?

also, the other mate forgot to take u^2