Free FE Practice Test# PrepFE™

## Free FE Environmental Example Practice Problems

We've selected 10 diverse practice problems from our question bank that you can use to review for the Environmental engineering FE exam and give you an idea about some of the content we provide.

◯ A.

$4+\sqrt{3}$

◯ B.

$2+\sqrt{7}$

◯ C.

$2-\sqrt{7}$

◯ D.

$4-\sqrt{3}$

◯ A.

0.9 m/s

◯ B.

1.8 m/s

◯ C.

2.4 m/s

◯ D.

0.2 m/s

◯ A.

they are generally organic compounds.

◯ B.

they are stable at high temperatures.

◯ C.

a combination of two or more materials differing in form or composition.

◯ D.

they are usually high density.

Answer true or false:

◯ A.

True

◯ B.

False

◯ A.

Decrease total solids concentration

◯ B.

Increase total solids concentration

◯ C.

Convert suspended solids into settleable solids

◯ D.

None of these - sludge dewatering makes no change at all in solids concentration

A. $4+\sqrt{3}$

B. $2+\sqrt{7}$

C. $2-\sqrt{7}$

D. $4-\sqrt{3}$

The correct answers are B and C.

A.0.9 m/s

B.1.8 m/s

C.2.4 m/s

D.0.2 m/s

The correct answer is B.

We know that flow in laminar flow conditions has a triangular distribution where the fluid is moving the fastest at the center of the pipe and moving the slowest near the borders of the pipe. For laminar flow in circular pipe conditions, one can calculate what the fluid velocity is anywhere along the pipe radius via: $$ v(r) = v_{max}\left[1-\left(\frac{r}{R}\right)^2\right] $$ where

$v_{max} = 2\bar{v}=2(2.5\si{m/s})=5\si{m/s}$

$R=\text{radius of the tube}=1\si{m}/2=0.5\si{m}$

$r=\text{distance from the centerline}=0.5\si{m}-(10\si{cm}/100)=0.4\si{m}$ $$ v(0.4\si{m}) = 5\si{m/s}\left[1-\left(\frac{0.4\si{m}}{0.5\si{m}}\right)^2\right] \\ v(0.4\si{m})=1.8\si{m/s} $$ Therefore, the fluid velocity 10 cm off the pipe border is 1.8 m/s

A.they are generally organic compounds.

B.they are stable at high temperatures.

C.a combination of two or more materials differing in form or composition.

D.they are usually high density.

The correct answer is A.

Plastics (or polymers) are generally organic compounds based upon carbon and hydrogen. They are very large molecular structures. Usually they are low density and are not stable at high temperatures. They can be readily formed into complex shapes. Their strength, stiffness, and melting temperatures are generally much lower than those of metals and ceramics. Their light weight, low cost, and ease of forming make them the preferred material for many engineering applications.

Answer true or false:

A.True

B.False

The correct answer is A.

A.Decrease total solids concentration

B.Increase total solids concentration

C.Convert suspended solids into settleable solids

D.None of these - sludge dewatering makes no change at all in solids concentration

The correct answer is B.