A $$non-viscous$$ liquid of constant density $$500kg/m3$$ flows in a variable $$cross-sectional$$ tube. The area of $$cross-section$$ of the tube at two points P and Q at heights of $$3m$$ and $$6m$$ are $$2$$×$$10$$−$$3$$ $$m2$$ and $$4$$×$$10$$−$$3$$ $$m2$$ respectively. the work done per unit volume by the forces of gravity as the fluid from point P to Q is:

Question

A $$non-viscous$$ liquid of constant density $$500kg/m3$$  flows in a variable $$cross-sectional$$ tube. The area of $$cross-section$$ of the tube at two points P  and Q  at heights of $$3m$$  and $$6m$$  are $$2$$×$$10$$−$$3$$ $$m2$$  and $$4$$×$$10$$−$$3$$ $$m2$$  respectively. the work done per unit volume by the forces of gravity as the fluid from point P  to Q  is:

Infinity Learn · Accepted Answer

Work done per unit volume by force of gravity  $$=$$−     change in $$PE$$ per unit volume∴      $$W=$$−Δ$$U=$$−ρ$$g(h2$$−$$h1)$$     $$=$$−ρ$$g(6$$−$$3)$$     $$=$$−$$3$$×$$500$$×$$9.8$$     $$=$$−$$1.47$$×$$104J/m3$$

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