Editor Staff asked 1 year ago
A motor is used to deliver water through a pipe. Let the motor have a power P initially. To double the rate of flow of water through the pipe, the power is increased to P’. What is the value of P’/P?
(a) 2
(b) 4
(c) 6
(d) 8
I got this question in class test.
I would like to ask this question from Power in chapter Work, Energy and Power of Physics – Class 11
Select the correct answer from above options
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Editor Staff answered 1 year ago
The correct answer is (d) 8
Easiest explanation: Power = Force x Velocity
= (Mass/Time) x Velocity^2
= Rate of flow x Velocity^2
Rate of flow = Area x Velocity
Doubling the rate of flow will double the velocity.
P = Rate of flow x Velocity^2
P’ = (2 x Rate of flow) x (2 x Velocity) ^2
= 8P
P/P’ = 8.
