Concepts Of Physics MCQ Edition [Volume 1]PhysicsFluid Mechanics
A closed cubical box is entirely filled with water and undergoes a horizontal acceleration a towards the right. The resultant normal force exerted by the water on the top of the box
Options
- Apasses through the centre of the top
- Bbecomes zero
- Cpasses through a point to the right of the centre
- Dpasses through a point to the left of the centre
Correct answer
D. passes through a point to the left of the centre
Step-by-step solution
When the box accelerates horizontally to the right with acceleration a , a pseudo force acts on the water towards the left. The pressure gradient in the horizontal direction is given by dP dx = - a , where is the density of water and x is the distance measured from the left face towards the right. This shows that the pressure decreases linearly from left to right. Therefore, the pressure on the top surface is maximum at the left edge and minimum at the right edge. The normal force exerted by the water on an element