Water flowing through a 2.8 cm-diameter pipe can fill a 200 L bathtub in 5.8 min.
Flow rate Q = volume/time = speed * cross section area
Q=200/5.8=speed*.028....i get 1231.52
or
Q=(200/348)=speed*.028...i get 20.52
both are wrong so what do i do?
then i did
speed=200/(pi*.25^2) ...i got 3.97 which is wrong
then i did v=Q/A=.2m^3/348s
divided by pi*(.014)^2 so i got 3.585559637e^-8...this is also wrong...plz look into it
YOu are not using units, nor labeling your work with units.
YOu are not using area, you are using diamter. Area= PI(diameter/2)^2
That would correct the top part, but you need to change liters to the same unit as area (cm, dm, or whatever).
I recommend diameter as .28dm, volume as 200 dm^3, that would give speed in dm/min. most would change that to dm/seconds.
You are relying on your calculator to think for you. There are multiple errors on each line.
Looking at how lost you are, I will do this for you one time only
flow rate: 200dm^3/(5.8*60) sec=.548dm^3/sec
speed= flow rate/area=.548dm^3/sec *1/(PI*(.28dm/2)^2)
= .548dm^3/sec * 1/.0616dm^2
=8.90dm/sec
Now. check that. Understand it. Finally, does the idiot computer expect answers in dm/sec? If not, think for it and convert.
Notice how I put units in each quantity.
Put your units in the calculations, do it with pen/pencil. Make the calculations check your work (you have to end with units that support the quantity).
I feel I'm being helped in Asia ...sorry to be pain in the neck. just a question if u don't mind...how do u convert from dm/s to m/s
dont worry i figured it out...i didn't have to convert...it was a problem of putting wrong brackets in my calculator
To calculate the flow rate of water flowing through a pipe and filling a bathtub, we can use the formula:
Flow rate (Q) = Volume / Time
Given that the volume of the bathtub is 200 L and the filling time is 5.8 min (348 seconds), we can proceed with the calculations.
1. First, convert the volume from liters to cubic meters:
Volume = 200 L = 0.2 cubic meters
2. Now, divide the volume by the time to find the flow rate:
Q = 0.2 cubic meters / 348 seconds ≈ 0.00057471 cubic meters/second
So, the flow rate is approximately 0.00057471 cubic meters per second.
But you're asking for the speed, which can be calculated by dividing the flow rate by the cross-sectional area of the pipe.
3. The pipe has a diameter of 2.8 cm, so its radius would be half of that:
Radius (r) = 2.8 cm / 2 = 1.4 cm = 0.014 meters
4. Calculate the cross-sectional area using the radius:
Area (A) = π * r^2 = π * (0.014)^2 ≈ 0.00061575 square meters
5. Finally, divide the flow rate by the cross-sectional area to find the speed:
Speed (v) = Q / A
v ≈ (0.00057471 cubic meters/second) / (0.00061575 square meters) ≈ 0.9336 meters/second
So, the speed of the water flowing through the pipe is approximately 0.9336 meters per second.
Please note that your previous attempts had incorrect calculations. By following the steps provided above, you should be able to obtain the correct answer.