Question
Question: A marble rolls down from top of a staircase with constant horizontal velocity u.If each step is y me...
A marble rolls down from top of a staircase with constant horizontal velocity u.If each step is y metre high and x metre wide, the marble just hits the edge of the nth step when n =

A
xu2/gy2
B
u2/gy
C
2yu2/gx2
D
4yu2/gx2
Answer
2yu2/gx2
Explanation
Solution
Total horizontal distance to be covered = x × n = nx.
But nx = ut ……….. (i)
and ny = 1/2 gt2 …………. (ii)
Substituting the value of t from (i) in (ii),
ny = 1/2 g n2x2/u2
or n = 2yu2/gx2