Question

a river 3m deep and 40 m wide is flowing at the rate of 2km per hour. How much water will fall into the sea in a minute?

Answer 1

Height = 3 m
Breadth = 40 m
length = 2km = 2000 m
time = 1 h = 60 mins
water / hour = 2000/ 60 = 100/3
Volume = l * b * h = 100/3 * 3 * 40 = 4000 m³ = 4000 * 10³ liters

Answer 2

so, in order to answer this question, let us analyse the given data
it says that the depth = 3 metres
                         width = 40 metres
and the rate of flow = 2 km per hour( converting this into metre per second, we get rate of flow = 2*(1000/3600)=2*(5/18)= 0.55 metre per second)
now we know that volume = length *width*height
similarly, volumetric rate of flow = length*width*rate of flow
which leaves us at v=3*40*0.55= 66.67 metre cube per second.
so the amount of flow per minute would be given by
 66.67*60 = 4000 metre cube per minute
pls do let me know if the answer helped