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Water trough being filled with water, related rates?
A triangular water trough is being filled with water at a rate of 3 ft^3/minute. How fast is the water level (depth) rising when the water is 6 inches deep, if the tank is 5 feet long and the ends are equilateral triangles with sides 3 feet long?
2 Answers
- GusBsAsLv 68 years agoFavorite Answer
I guess that the ends of the tank are triangles with their bases on the top...
If the tank has a level of x (in ft), its filled volume is the volume of a triangular prism whos base has a height of x. As the triangles are equilateral, x and B satisfy:
x/B = sin(60°) = (√3)/2.
Then the area of the triangle (the section under water) is
A(x) = (1/2) B x = (1/2) (2x/(√3)) x = x² / √3.
The volume of water is then
V(x) = A(x) L = 5 x² / √3.
This volume is increasing at a rate of 3 (cubic ft by minute), then
dV/dt = dV/dx dx/dt = (10/√3) x dx/dt = 3
=>
dx/dt = (3√3/10)/x
and when x = 6 in = 0.5 ft
dx/dt (x=0.5) = 3√3/5 = 1.039 ft/min
- Anonymous5 years ago
There could desire to be an overabundance of water troughs contained in the calculus international. it extremely is the third such question i've got responded in as many day. I be conscious that the numbers contained in the question do not experience the numbers on your "answer". right here is answer utilizing numbers in question: First, we could desire to apply comparable measurements (m) for all dimensions: Water trough is 10 m long circulate section is shape of isosceles trapezoid 20 cm = 0.2 m huge at backside 80 cm = 0.8 m huge at precise has height 60 cm = 0.6 m component of trapezoid = h * (b? + b?)/2 quantity of trapezoidal trough = h * (b? + b?)/2 * L ---------- the subject with looking quantity of in part crammed trough is that b? variations with height. while h = 0, b? = b? = 20cm = 0.2 m while h = 0.6, b? = 80 cm = 0.8 m when you consider that distinction between bases is 0.8m - 0.2m = 0.6m and h=0.6m, then width of precise base will enhance by utilizing 0.1m for each 0.1m enhance in height. so we are able to specific b? = 0.2 + h Now we are able to rewrite equation for quantity as function of h: V = h * (b? + b?)/2 * L the place b? = 0.2, b? = 0.2 + h, L = 10 V = h * (0.2 + 0.2 + h)/2 * 10 V = 10h * (h + 0.4) / 2 V = 5h² + 2h ---------- Water enters at fee of 0.one million m³/min dV/dt = 0.one million Water is 50 cm = 0.5 m deep h = 0.5 how briskly is water point increasing? locate dh/dt V = 5h² + 2h dV/dt = (10h + 2) dh/dt ----> as much as date: I had 5h+2 earlier dh/dt = (dV/dt) / (10h + 2) dh/dt = 0.one million / (10*0.5 + 2) dh/dt = 0.one million / 7 dh/dt = one million/70 = 0.0143 So water point is increasing at fee of 0.0143 m/min or one million.40 3 cm/min ==================== ==================== i might have achieved calculations utilizing numbers on your "answer", yet i'm undecided if H = .4m refers back to the peak of the trough or the peak of the water. to unravel, i want the two heights.