FE Civil Engineering Exam Prep #5

Question 1

A 40.0 gram sample of a radioactive element decays to 5.0 grams in 15 hours. What is the half-life of this element?

Accepted Answer

5 hours

Answer

Radioactive decay occurs at a constant half-life, meaning the amount of the substance halves over a fixed period. Starting with 40.0 grams, it decays to 20.0 grams after one half-life, then to 10.0 grams after a second half-life, and finally to 5.0 grams after a third half-life. Since this entire process took 15 hours, and it involved three half-lives, each half-life must be 15 hours / 3 = 5 hours.

Question 2

Which of the following species is classified as an electrolyte?

Accepted Answer

Na+

Answer

An electrolyte is a substance that produces an electrically conducting solution when dissolved in a polar solvent, typically water, because it dissociates into ions. Na+ is a sodium ion, which is already in an ionic form and readily exists in solution, contributing to electrical conductivity. The other options (CH4, C6H12O6, N2, O3) are covalent compounds or elements that do not dissociate into ions in water and are therefore non-electrolytes.

Question 3

Which of the following elements displays bonding characterized by a delocalized “sea of electrons?”

Accepted Answer

Copper

Answer

Copper is a metal, and metals are characterized by metallic bonding. In metallic bonding, valence electrons are delocalized and shared among a lattice of positively charged metal ions, forming a 'sea of electrons.' This allows for high electrical and thermal conductivity, which are characteristic properties of metals like copper.

Question 4

Euler’s Formula is used to determine which of the following properties related to a simply-supported column?

Accepted Answer

Critical buckling load

Answer

Euler's Formula is a fundamental equation in structural engineering used to calculate the critical buckling load for slender columns. This load represents the maximum axial compressive force a column can withstand before it suddenly deflects laterally, or buckles. The formula considers the column's material properties, cross-sectional geometry, and effective length.

Question 5

The hydraulic radius of a sewer refers to which of the following?

Accepted Answer

The ratio of the cross-sectional area of flow to the wetted perimeter

Answer

The hydraulic radius is a crucial geometric property used in open-channel flow calculations, such as those for sewers. It is defined as the ratio of the cross-sectional area of the fluid flow to the wetted perimeter, which is the portion of the channel perimeter in contact with the flowing fluid. This parameter is essential for determining flow velocity and discharge using equations like the Manning equation.

Uncategorized Practice Test

Uncategorized Practice Test

FE Civil Engineering Exam Prep #5