Frequently asked questions

Ten areas with about 100 topics each. In every area topics run in order from Beginner (first third) to Intermediate to Advanced, so you can follow a clear learning path.

Use the search box at the top (press / to focus it). It searches titles, explanations and area names; every word you type must match. Use the filters on the results page to narrow by area or level.

Yes. Completed topics, bookmarks, quiz results and your study streak are stored in your browser using localStorage. Clearing site data will remove them, and nothing is sent to a server.

Quizzes give instant feedback and an explanation after every answer, so they are for learning. Tests are timed, show no answers until the end, and finish with a graded report and review.

Interactive simulations (projectile motion, damped oscillator, RC circuit, Fourier series, beam bending, PID control, sorting, aliasing and AC power). Move the sliders and see the maths respond in real time.

Yes. The layout is responsive and the simulations support touch.

After the page has loaded once, everything runs locally in your browser; there are no network calls. You can also host the dist folder on any static server.

Topics on sampling, PID control, RC circuits, oscillators, AC power, beam bending, projectile motion and sorting link automatically to the matching lab. Look for the "See it in action" section on a topic page.

It records that you have studied a topic. The discipline progress ring and your study streak on the progress page update from these marks.

Each press of "Another question" draws a different question from the question bank for that topic, so repeated practice covers more ground.

Yes. Each topic has a static page under /learn/ that includes the explanation, key points, use cases, FAQs and links to related topics. The interactive lesson with quizzes and labs is at /topic/.

Try the beginner topics from several areas. Choose the one where you enjoy the problems, not just the job titles. Mathematics and Mechanics are shared foundations of nearly every branch.

Algebra, trigonometry and basic calculus are enough to start. Linear algebra, differential equations and probability become important for advanced work in control, signals, mechanics and machine learning.

Read the explanation, try to restate it in your own words, test yourself with the quick check, then apply it with a worked problem or a simulation. Revisit after a few days (spaced repetition).

At 5 topics a day it takes roughly 200 days. Depth matters more than speed; use the progress page to pace yourself.

Memorise only a few fundamentals. Understand where formulas come from and what each term means, and you can look up or re-derive the rest.

Draw a diagram, list knowns and unknowns, check units, solve symbolically before plugging numbers, and sanity-check the answer with an estimate.

A mismatch in units has destroyed real spacecraft. Dimensional analysis catches mistakes early and is a quick consistency check.

Python for analysis and automation, C or C++ for embedded systems, and MATLAB or Julia in some fields. Learn Git and basic data handling too.

Very. Building a robot, a circuit, a small bridge model or a web tool shows gaps that reading cannot, and it makes a portfolio.

Read each use case and ask how the topic would change a design decision in that situation. Explaining one use case in your own words reveals gaps faster than re-reading.

Go back to the earlier topic named in the FAQ on the topic page, work one example by hand, then return. Skipping ahead without the foundations usually costs more time.

No. Start with the foundations, mathematics and mechanics, or electronics, then add the disciplines that match your goals. Many areas share the same tools.

Stress is internal force per unit area (Pa). Strain is relative deformation (dimensionless). Their ratio in the elastic range is the elastic modulus.

Temperature is a measure of average molecular kinetic energy. Heat is energy transferred because of a temperature difference.

Transformers can easily step AC voltage up to reduce current and losses over long distances, then step it down for use. HVDC is now also used for very long links.

When a periodic force matches a natural frequency, amplitude grows dramatically. It can fatigue and destroy structures, as in the Tacoma Narrows bridge failure.

Measuring the output, comparing it to the target, and using the error to adjust the input. Thermostats and cruise control work this way.

A way to describe how an algorithm's time or memory grows with input size, ignoring constant factors. O(log n) grows much slower than O(n²).

Analog signals vary continuously; digital signals use discrete levels, usually two, which resist noise and are easy to store and process.

The ratio of strength to expected load. It covers uncertainty in loads, materials and workmanship; typical values range from 1.5 to 4 or more.

A measure of how spread-out energy is, or how many microscopic arrangements match a state. The second law says it never decreases in an isolated system.

They give natural frequencies of structures, stability of control systems, principal stresses, and principal components in data analysis.

The minimum sampling rate, twice the highest signal frequency, needed to avoid aliasing when digitising a signal.

The time an exponential response takes to reach about 63 percent of its final change, written as tau. For an RC circuit tau equals R times C.

Accuracy is how close a result is to the true value. Precision is how repeatable the results are. A good measurement needs both.

The probability of seeing results at least as extreme as yours if the null hypothesis were true. It is not the probability that the hypothesis itself is true.

Mechanical: machines and energy. Civil: infrastructure. Electrical: power, electronics and communications. Software: computing systems. Many modern products need all four.

Most regulated engineering roles require an accredited degree; software and some technician roles also accept equivalent experience. Check requirements in your country.

A licence or charter awarded after education, experience and examination, needed to sign off public-safety designs in many places.

Be solid on fundamentals in your area, practise explaining your projects, and rehearse estimation problems and basic design trade-offs aloud.

Renewable energy, electric vehicles, robotics, embedded AI, semiconductors, biomedical devices and infrastructure resilience all have strong demand.

Read standards and journals, follow open courses, join professional societies, and keep building small projects.

Two or three projects with a clear problem, the data you used, the design decisions you made and the results. Written reports, diagrams and working code matter more than certificates.

It depends on the field. Many industry roles accept a bachelor's degree backed by strong projects, while research and some specialist roles usually expect postgraduate study.