Question

A ball rolls of the top of the stairway with a horizontal velocity u ms⁻¹. If the steps are h m high and b m wide, the ball will hit the edge of the n^th step, if:

Options

• n = `(2"hu")/("gb"^2)`

• n = `(2"hu"^2)/("gb")`

• n = `(2"hu"^2)/("gb"^2)`

• n = `"hu"^2/"gb"^2`

Answer 1

n = `(2"hu"^2)/("gb"^2)`

Explanation:

∵ R = `"u" sqrt((2"H")/"g")` ....(horizontal projection)

nb = `"u"sqrt((2"nh")/"g")`

⇒ n = `(2"hu"^2)/("gb"^2)`