{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

homework3_solns

# homework3_solns - Homework 3 Fluid Mechanics CE 3502 Fall...

This preview shows pages 1–2. Sign up to view the full content.

Homework 3 Fluid Mechanics CE 3502 Fall, 2008 (1) Water strikes a block as shown and is deflected 30°. The flow rate of the water is 1.50 kg/s, and the mass of the block is 1.30 kg. The coefficient of static friction between the block and the surface is 0.100 (friction force / normal force). If the force parallel to the surface exceeds the frictional force, the block will move. Find the maximum initial velocity (V) such that the block will not slip. Neglect the weight of the water. Find: maximum initial water velocity (V) such that the block will not slip. Solution: Use conservation of momentum for the stationary control volume with control surface as shown: Force / Free body diagram Momentum diagram W block F normal F friction 30° V m & V m & Conservation of momentum in the x direction: ( ) ( ) + ρ = CS IN x CS OUT x CV x x v m v m V d v F & & For the one inlet and outlet, as shown, V IN = V OUT , so given the information in the drawing: v x,IN = V, and v x,OUT = Vcos30° There is no accumulation in the control volume, so ( ) ( ) ( ) ( ) V 2 3 1 s / kg 50 . 1 F V s / kg 50 . 1 2 3 V s / kg 50 . 1 0 F friction friction = + = Conservation of momentum in the y direction: ( ) ( ) + ρ = CS IN y CS OUT y CV y y v m v m V d v F & & v y,IN = 0, and v y,OUT = Vsin30°, and there is no accumulation in the control volume, so ( ) ( ) ( ) ( ) ( ) ( ) N 75 . 12 V s / kg .75 0 s / m 81 . 9 kg 30 . 1 V s / kg .75 0 F 2 / 1 V s / kg 50 . 1 0 W F 2

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

### Page1 / 3

homework3_solns - Homework 3 Fluid Mechanics CE 3502 Fall...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online