Turbo Machines - Mechanical Engineering (MCQ) questions and answers for Q. 10895

Q.  What is the formula for forces exerted by fluid on a body?
- Published on 16 Sep 15

a. (Rate of momentum in) x (Rate of momentum out)
b. (Rate of momentum in) – (Rate of momentum out)
c. (Rate of momentum in) + (Rate of momentum out)
d. None of the above

ANSWER: (Rate of momentum in) – (Rate of momentum out)

Related Content

 

    Discussion

  • Pankaj   -Posted on 06 Oct 15
    We know that the product of mass and velocity is called as momentum.

    ∴ Momentum = m x V

    Magnitude of applied force is rate of change of momentum

    ∴ Applied force F = d/dt (m x V)

    On differentiating the above equation,

    F = (m x (dV/dt)) + (V x (dm/dt))

    In solid bodies mass of body remains constant,

    ∴ dm/dt = 0

    F = (m x (dV/dt))

    ∴ F = m x dV/dt

    = (m/t) (V2 – V1 )

    Mass flow rate of fluid, ṁ = (m/t) = ρ x Q

    Therefore force exerted by the body on fluid is given by,

    F = ρ Q (V2 – V1 )

    Thus the force exerted by fluid on body will be equal and opposite to the force exerted by the body on fluid.

    F = ρ Q (V1 – V2 )

    Therefore,

    Force exerted by fluid on body = Rate of momentum in (ṁ V1) – Rate of momentum out (ṁ V2)

➨ Post your comment / Share knowledge


Enter the code shown above:

(Note: If you cannot read the numbers in the above image, reload the page to generate a new one.)
▲