Knowledge area 5 of the FE Civil exam: 4–6 of the 110 questions. The subtopics NCEES lists, how they are tested and worked practice problems with solutions.
110 questions on the real 5 hours 20 minutes clock, weighted to the NCEES specifications, with a score by knowledge area and a worked solution for every answer.
Or start the free Dynamics drillFrom the NCEES FE Civil CBT exam specifications, knowledge area 5.
Dynamics questions cover motion of particles and rigid bodies: constant-acceleration kinematics, projectiles, Newton’s second law, work-energy and impulse-momentum. Choose the method from what is given: forces and acceleration point to Newton’s law, speeds and distances to work-energy, times and velocities to impulse-momentum.
On exam day the relationships you need are in the Reference Handbook section on Dynamics. The handbook is the only reference allowed, so practice finding each formula in it rather than memorizing a separate sheet.
Work each problem with your calculator and the handbook, then open the solution.
Problem 1 · Mass moment of inertia
A slender uniform rod has a mass of 3.0 kg and a length of 1.2 m. Its mass moment of inertia about a perpendicular axis through one end is most nearly:
Answer: B: 1.44 kg·m²
I_end = mL²/3 = 3.0(1.2)²/3 = 1.44 kg·m². Equivalently, mL²/12 + m(L/2)² = 0.36 + 1.08 = 1.44 kg·m².
Mass moment of inertia · Reference Handbook: Dynamics
Problem 2 · Work-energy of rigid bodies
A solid uniform disk of 20 kg mass and 0.50 m radius rolls without slipping along a level floor; its center moves at 3.0 m/s. What is its total kinetic energy? Enter the value in joules to the nearest joule.
Fill in the blank: answer in J.
Answer: 135 J (accepted 133 to 137)
KE = ½mv² + ½Iω² with I = ½mr² and ω = v/r, so KE = ½mv² + ¼mv² = ¾mv² = 0.75(20)(3.0)² = 135 J.
Work-energy of rigid bodies · Reference Handbook: Dynamics
Problem 3 · Newton's second law for rigid bodies
A solid uniform disk of 50 kg mass and 0.40 m radius rotates about its central axis in frictionless bearings. A constant 30 N·m torque is applied. Its angular acceleration is most nearly:
Answer: D: 7.50 rad/s²
I = ½mr² = ½(50)(0.40)² = 4.0 kg·m². α = T/I = 30/4.0 = 7.50 rad/s².
Newton's second law for rigid bodies · Reference Handbook: Dynamics
Problem 4 · Kinematics of particles
Select all that apply.
A particle moves along a curved path at constant speed. Which statements are true? Select all that apply.
Answer: A: Its tangential acceleration is zero; B: Its normal acceleration equals v²/ρ, where ρ is the radius of curvature; D: Its velocity is tangent to the path
Constant speed means a_t = dv/dt = 0, but the direction of velocity, which is always tangent to the path, keeps changing, so a_n = v²/ρ directed toward the center of curvature.
Kinematics of particles · Reference Handbook: Dynamics
More FE Civil practice problems from every knowledge area
Sit the full exam under the real clock
110 questions on the real 5 hours 20 minutes clock, weighted to the NCEES specifications, with a score by knowledge area and a worked solution for every answer.
Or start the free Dynamics drillThe NCEES FE Civil specification lists 4–6 questions on Dynamics, out of 110. Every examinee gets the same number per knowledge area.
Kinematics (e.g., particles, rigid bodies); Mass moments of inertia; Force acceleration (e.g., particles, rigid bodies); Work, energy, and power (e.g., particles, rigid bodies).
In the NCEES FE Reference Handbook, which appears on screen during the exam: the Dynamics section. Practice with your free copy from MyNCEES so you know where each relationship sits.
Original independent practice questions written to the published NCEES exam specifications. Not affiliated with or endorsed by NCEES (National Council of Examiners for Engineering and Surveying).