A staircase contains three steps each 10 cm high and 20 cm wide (figure 3-E9). What should be the minimum horizontal velocity of a ball rolling off the upper
most plane so as to hit directly the lowest plane?


Given:
Height of one step = 10 cm
Width of one step = 20 cm



Total height of the staircase = y = 30 cm
Total width of the staircase = x = 40 cm


Capture.PNG


To directly hit the lowest plane, the ball should just touch point E.
Let point A be the origin of reference coordinate.
Let u be the minimum speed of the ball.
We have:





⇒


⇒


Thus, the minimum horizontal velocity of the ball is 2 m/s.


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