Question 1

Which of the following best describes the physical meaning of pressure in a fluid, as illustrated in the first image?

Accepted Answer

Pressure is the force exerted normal to the surface area of the boundary, divided by the area.

Question 2

A fluid is at rest in a tank. According to the second image, what is the relationship between the pressures at two different depths $$y_1$$ and $$y_2$$?

Accepted Answer

$$p_2$$ = $$p_1$$ + \rho g ($$y_1$$ - $$y_2$$)$$

Question 3

In the third image, a piston applies an external pressure $$p_{ext} to a $$liquid. According to Pascal’s Principle, what happens to the pressure at point $$P$$ when $$p_{ext} is $$increased?

Accepted Answer

The pressure at $$P$$ increases by the same amount as $$p_{ext}.$$

Question 4

Referencing the fourth image, which scenario results in a net upward force on the object submerged in water?

Accepted Answer

When the object's mass is less than the mass of water displaced.

Question 5

An iceberg floats in seawater as shown in the fifth image. If the density of ice is $$917\ 	ext{kg/m}^3$$ and the density of seawater is $$1024\ 	ext{kg/m}^3$$, what fraction of the iceberg is visible above water?

Accepted Answer

$$1 - \frac{917}{1024}$$

Question 6

In the context of the sixth image, which statement about the flow speed and cross-sectional area in a tube of flow is correct?

Accepted Answer

The flow speed is higher where the cross-sectional area is smaller.

Question 7

According to the seventh image, what is the direction of the velocity vector of a fluid element relative to the streamline?

Accepted Answer

The velocity vector is tangent to the streamline.

Question 8

A horizontal pipe narrows from diameter $$d_1 to$$ $$d_2 as $$shown in the eighth image. If the speed at the narrow end is $$v_1 = 15$$\ 	ext{m/s}$$, what is the speed v_2$ at the wider end?

Accepted Answer

$$v_2$$ = \left(\frac{$$d_1$$}{$$d_2$$}\$$right)^2$$ $$v_1$$

Question 9

Which equation expresses the continuity of mass flow for an ideal fluid?

Accepted Answer

$$\$$rho_1$$ A_1$ v_1$ = \$$rho_2$$ A_2$ v_2$

Question 10

A fluid flows through a pipe of constant cross-section at different elevations. According to Bernoulli’s equation, what happens to the pressure as the elevation increases?

Accepted Answer

The pressure decreases as the elevation increases.

Question 11

A block of wood floats in water. If the density of the wood is $$600\ 	ext{kg/m}^3$$ and the density of water is $$1000\ 	ext{kg/m}^3$$, what fraction of the block’s volume is submerged?

Accepted Answer

$$\frac{600}{1000}$$

Question 12

Which of the following statements about an ideal fluid is correct?

Accepted Answer

An ideal fluid is incompressible and nonviscous.

Question 13

A submerged object experiences a buoyant force. What is the magnitude of this force?

Accepted Answer

$$F_b = m_f g$$

Question 14

If a fluid is in static equilibrium, what can be said about the net force on any selected volume of the fluid?

Accepted Answer

The net force is zero.

Question 15

A fluid element traces out a streamline as it moves. Which property is true for streamlines in an ideal fluid?

Accepted Answer

Streamlines never intersect.

Question 16

A sample is fully submerged in water. If its density is greater than water, what will happen according to Archimedes’ principle?

Accepted Answer

It will sink to the bottom.

Question 17

What is the apparent weight $$W_{app} of a $$body immersed in a fluid?

Accepted Answer

$$W_{app} = W - F_b$$

Question 18

Which of the following is NOT a property of an ideal fluid?

Accepted Answer

Compressible

Question 19

If the pressure at the surface of a fluid is $$p_0$$ and the depth is $$h$$, what is the pressure at depth $$h$$?

Accepted Answer

$$p = p_0$ + \rho g h$$

Question 20

According to Bernoulli’s equation, what happens to the pressure in a horizontal pipe when the flow speed increases?

Accepted Answer

The pressure decreases.

Fluids: Density, Pressure, Buoyancy, and Fluid Dynamics

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