Froude Number Formula


Froude Number Formula

Froude number was termed after William Froude is a dimensionless number defined as the ratio of characteristic velocity to the gravity wave velocity. 

Where, the characteristic velocity is v and

the characteristic wave velocity is c,

gravity in terms of the Froude number is articulated as,

Froude number is Fr,

velocity is v,

gravity is g,

characteristic length is l.

It is used to specify the resistance of a body which is immersed partially moving along with water.

Froude Number Solved Problems

Underneath are some of the solved problems based on Froude Number:

Problem 1: Find the Froude number if the length of the boat is 2m and velocity is 10 m/s.

Known: length l = 2m, velocity v = 10 m/s

The Froude number is articulated as,

Thus, the Froude number of the boat is 0.451.


Problem 2: Compute the velocity of the moving fish in the water if its length 0.5 m and Froude number is 0.72.


Known: l (length) = 0.5m, Fr (Froude number) = 0.72

The Froude number is given by,

Thus, the velocity of the moving fish is 1.59 m/s.


Practise This Question

The diagram shows a capacitor C and a resistor R connected in series to an ac source. V1 and V2 are voltmeters and A is an ammeter

Consider now the following statements

1) Readings in A and
V2 are always in phase
Reading in V1 is ahead in phase with reading in V2
3) Readings in A and V1 are always in phase which of these statements are / is correct

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