Tag: moving through fluids

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Questions Related to moving through fluids

Multiple choice physics dynamics - explaining motion air resistance fluid friction moving through fluids

If we drop a cup of water on a plate and a cup of oil on another plate, water is seen to spread faster along diameter. This is an example related to:

  1. fluid friction

  2. rolling friction

  3. sliding friction

  4. static friction
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

This example relates to fluid friction. Speed of spreading of a volume of liquid depends on the liquid friction.Friction offered by water is less as its density is less than oil.

Multiple choice physics dynamics - explaining motion air resistance fluid friction moving through fluids

Which of the following statements indicates advantage of fluid friction?

  1. Walking on road

  2. Rolling stone on carpet

  3. Lubricating machine parts

  4. None of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Lubricating machine parts indicates advantage of fluid friction. This helps in lowering the friction and thus helps to keep parts of machinery in good condition for some time. 

Multiple choice physics dynamics - explaining motion air resistance fluid friction moving through fluids

A spherical body of radius R consists of a fluid of constant density and is in equilibrium under its own gravity. If$ P(r)$ is the pressure at $r(r < R)$, then the correct option(s) is(are)?

  1. $P(r=0)=0$
  2. $\dfrac{P(r=3R/4)}{P(r=2R/3)}=\dfrac{63}{80}$
  3. $\dfrac{P(r=3R/5)}{P(r=2R/5)}=\dfrac{16}{21}$
  4. $\dfrac{P(r=R/2)}{P(r=R/3)}=\dfrac{20}{27}$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

For a fluid sphere under gravity, the pressure distribution follows hydrostatic equilibrium. Calculating the ratio of pressures at the specified radii confirms the result in option B.