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CG PET Fluids — practice questions

Explore 20 free Fluids questions in CG PET Physics. Open each question or exercise to read its content, reference answers and available explanation.

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Fluids questions and exercises with answers

Showing questions 1–20 of 20.

An **ideal fluid** has all the following properties EXCEPT:Read the answer and worked solution →The pressure $p$ at depth $h$ below the free surface of a liquid of density $\rho$ (in addition to atmospheric pressure $p_0$) is:Read the answer and worked solution →The **SI unit** of pressure is:Read the answer and worked solution →A **mercury barometer** measures:Read the answer and worked solution →**Reynolds number** is used to distinguish:Read the answer and worked solution →**Viscosity** of most liquids with rising temperature:Read the answer and worked solution →**Stokes' law** gives the viscous drag on a small sphere of radius $r$ moving with velocity $v$ through a fluid of viscosity $\eta$ as:Read the answer and worked solution →The phenomenon of rise (or fall) of a liquid in a narrow capillary tube is called:Read the answer and worked solution →The condition for **terminal velocity** of a sphere falling in a viscous fluid is that:Read the answer and worked solution →A swimmer dives to 6 m below the water surface. The gauge pressure on her (water density = 1000 kg/m³, $g = 9.8$ m/s²) is:Read the answer and worked solution →A hydraulic lift uses a small piston (area 1 cm²) and a large piston (area 100 cm²). To lift a 1000 kg load, the minimum force needed on the small piston is:Read the answer and worked solution →Two liquids of densities $\rho_1$ and $\rho_2$ exert the same pressure. The ratio of their column heights $h_1 : h_2$ equals:Read the answer and worked solution →A capillary tube of radius $r$ dipped in a liquid of surface tension $T$ and density $\rho$, contact angle $\theta$, gives rise (or fall) to height $h$ where:Read the answer and worked solution →A steel ball of radius 0.3 mm falls at 2 m/s through glycerine ($\eta = 0.833$ N·s/m²). The viscous drag is:Read the answer and worked solution →A liquid flowing through a tube has Reynolds number $R_n = 500$. Its flow is:Read the answer and worked solution →The pressure at the **top of a column of water** open to atmosphere is approximately:Read the answer and worked solution →The **excess pressure** inside a spherical liquid drop of radius $r$ and surface tension $T$ is:Read the answer and worked solution →The excess pressure inside a **soap bubble** of radius $r$ and surface tension $T$ is:Read the answer and worked solution →A drop of water of radius 1 mm is broken into 1000 droplets of equal size. The ratio of total surface area after : before equals:Read the answer and worked solution →Pop what an ideal fluid really isRead the answer and worked solution →

Worked practice questions

An **ideal fluid** has all the following properties EXCEPT:

  1. Incompressible (constant density)
  2. Non-viscous (zero internal friction)
  3. Irrotational and steady flow
  4. Very high viscosity
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Correct answer: D. Very high viscosity

**Ideal fluid:** incompressible, irrotational, non-viscous, steady flow. High viscosity contradicts the non-viscous requirement. Real fluids deviate from ideality in all four respects.

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The pressure $p$ at depth $h$ below the free surface of a liquid of density $\rho$ (in addition to atmospheric pressure $p_0$) is:

  1. $p = p_0 - h\rho g$
  2. $p = p_0 + h\rho g$
  3. $p = h\rho g$ only
  4. $p = p_0 / (h\rho g)$
Show answer and solution

Correct answer: B. $p = p_0 + h\rho g$

Total pressure (absolute) at depth $h$ = atmospheric + liquid column pressure = $p_0 + h\rho g$. Gauge pressure is just $h\rho g$ (excluding $p_0$).

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The **SI unit** of pressure is:

  1. dyne/cm²
  2. Pascal (Pa) = N/m²
  3. atm
  4. torr
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Correct answer: B. Pascal (Pa) = N/m²

1 Pa = 1 N/m². 1 bar = 10⁵ Pa. 1 atm ≈ 1.013 × 10⁵ Pa. dyne/cm² is the CGS unit; torr is mmHg.

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