Question

A closed cubical box is completely filled with water and is accelerated horizontally towards right with an acceleration α. The resultant normal force by the water on the top of the box
(a) passes through the centre of the top
(b) passes through a point to the right of the centre
(c) passes through a point to the left of the centre
(d) becomes zeros

Answer 1

The resultant normal force by the water on the top of the box passes through a point to the left of the centre.

Explanation:

1. In case of filled box, pressure distribution on top of box surface is zero at right side and maximum at left side.

2. But pressure distribution is linearly increase from right to left.

3. So force distribution is also vary linearly from right to left.

4. From figure, it is clear that pressure is zero at top-right side of container. So force is also zero at top-right side of container.

5. From figure, it is clear that pressure is maximum at top-left side of container. So force is also maximum at top-left side of container.

6. Then force distribution like in form of triangle.

7. Then resultant force is pass through centre of gravity of triangle.

8. So resultant force is pass through one third of box width from left side of box