AIIMS2015Physics-Current Affairs

AIIMS 2015 Physics State Government Schemes MCQ Question

Type: MCQ-fact-Medium-Class 11

Determine the height above the dashed line XXXX' attained by the water stream coming out through the hole situated at point B in the diagram given below. Given that h=10 mh = 10\text{ m}, L=2 mL = 2\text{ m} and d=30d = 30^\circ.

Question diagram
A

10 m

B

7.1 m

C

5 m

D

3.2 m

Correct Answer

Option D

Detailed Explanation

Step 1: Find the height of the nozzle exitThe nozzle has a length LL and is inclined at an angle α=30\alpha = 30^\circ above the reference line XXXX'. The vertical height (y0y_0) of the nozzle's exit mouth above the line XXXX' is:y0=Lsinα=2×sin(30)=2×0.5=1 my_0 = L \sin\alpha = 2 \times \sin(30^\circ) = 2 \times 0.5 = 1\text{ m}Step 2: Find the velocity of efflux (vv)The depth of the exit nozzle below the free surface of the water is hy0h - y_0. Applying Torricelli's Law, the velocity of the water leaving the nozzle is:v = \sqrt{2g(h - L \sin\alpha)}$$$$v^2 = 2g(10 - 1) = 2g(9) = 18gStep 3: Determine the maximum height reached by the water projectileOnce the water leaves the nozzle, it acts as a projectile launched at an angle α=30\alpha = 30^\circ. The maximum vertical height (HprojH_{\text{proj}}) it can reach above its launch point is given by:Hproj=v2sin2α2gH_{\text{proj}} = \frac{v^2 \sin^2\alpha}{2g}Substitute v2=18gv^2 = 18g and sin(30)=0.5\sin(30^\circ) = 0.5 into the equation:Hproj=18g×(0.5)22g=18×0.252=2.25 mH_{\text{proj}} = \frac{18g \times (0.5)^2}{2g} = \frac{18 \times 0.25}{2} = 2.25\text{ m}Step 4: Calculate total height above the reference line XXXX'The total height attained above the line XXXX' is the initial exit height plus the maximum height of the projectile path:Htotal=y0+Hproj=1 m+2.25 m=3.25 mH_{\text{total}} = y_0 + H_{\text{proj}} = 1\text{ m} + 2.25\text{ m} = 3.25\text{ m}Rounding to one decimal place gives 3.2 m3.2\text{ m}, which matches option (d).

Found an issue with this question?