4 Hardest Mechanical Engineering Classes

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Mechanical engineering is a hard major, no matter how you slice it. There is no single course that is objectively the hardest in the major. Take any class and you can find someone who considered it to be their hardest class.

Content matter, instructor quality, and course load are all factors that will affect how difficult or easy you perceive a class to be. Classes are taught differently at every university, and everyone has their own opinions on how hard different classes are. This is a list of the classes that are generally regarded as the hardest courses in the mechanical engineering major.

Quick Links:

  1. The General Calculus/Physics Courses
  2. Thermodynamics
  3. Fluid Dynamics
  4. Controls/Vibrations

1. The General calculus/Physics Courses

This probably isn’t what you were expecting, but let us explain. By general calcs/physics, we mean calculus 1-3 and physics 1 and 2. If you ask engineering students which class they got their lowest grade in, often it will be one of the calculus or physics courses. This is for a few reasons:

It’s one of the first hard classes you take in college

It can take a while to get adjusted to college. The classes are bigger and more difficult. They’re set up in a way you’re not used to, and you don’t know how to study yet. Combining a difficult class with the first few months of college is a hard thing to do. A lot of times students learn how to study for college classes in calculus and physics, and it can take some trial and error.

The professors usually don’t care as much

At most Universities, professors must teach at least one class to be able to conduct research. When a professor doesn’t want to teach, they’ll pick up an entry-level course such as calculus or physics. It’s typically standardized and easier to teach. But if you’re one of 200 students in a lecture-hall-sized classroom with a professor that doesn’t want to be there, it’s probably not going to be a great time.

Also, since it’s considered an entry-level course, professors tend to forget that difficulty is relative. It’s hard for them to understand how Physics 1 can be hard when they have a PhD in the subject. It would be like you trying to help a fifth-grader with their math homework and not understanding how they don’t understand fractions.

Professors in the upper-level courses generally have more of a passion for teaching and will work harder to make the class enjoyable for students.

There’s a lot of them

There are three core calculus classes and two core physics classes, that’s five classes. One of them is bound to not “click” with you. It’s debatable, but a popular opinion is that calculus 2 and physics 2 are the hardest of the series. Don’t let this deter you, though. Everyone has a different opinions and experiences with the classes.

2. Thermodynamics

Thermodynamics is a hard class because of the subject matter. Thermodynamics, heat transfer, and fluids are all based on the same core principles and are all infamously known to be very difficult classes. Thermodynamics typically comes before heat transfer and fluids. It lays the groundwork for these future classes and it is your first exposure to the subject.

This is one of the first classes that students have no previous exposure to. With calculus and physics, you’ve probably had at least a brief introduction in high school. Thermodynamics is full of new concepts that you’ve never heard of before. It is brand new content, and difficult to understand, especially if you have a not-so-great professor.

3. Fluid Dynamics

hardest mechanical engineering classes fluid dynamics

Fluid Dynamics is thought to be the hardest of mechanical engineering classes. With heat transfer, at least you’ve had some exposure to it in thermodynamics, but there isn’t an “intro” to fluid dynamics. You hit the ground running and never stop.

Part of the difficulty is that it’s impossible to teach everything and cover every type of problem during lecture. It takes a lot of critical thinking and combining principles to solve fluid dynamics questions. The questions are very complex and it’s hard to fake your way through the class.

Furthermore, it’s a very cumulative class. In other classes, if you don’t understand a chapter, you might do poorly on an exam at worst, but then you can just move on to a different topic. In fluid dynamics, it’s important to understand all the concepts, as they build on each other. Every chapter adds new concepts, but you still need the previous ones to solve problems successfully.

4. Controls/Vibrations

We lump controls and vibrations together because they actually have a lot of overlap, content-wise. Between controls and vibrations, the harder one will probably be whichever one comes first or has the worse teacher.

The three “sectors” of mechanical engineering most people go into are manufacturing, thermodynamics (including thermo, heat transfer, and fluids), or controls. Most universities focus their curriculum on the first two areas, leaving controls on the back burner.

Controls and vibrations are unlike any other classes in the mechanical engineering degree. For many students, controls and vibrations can seem like an afterthought. They usually aren’t pre-requisites for anything and have very few pre-requisites themselves. They are the random classes you throw into your schedule when they fit.

Controls and vibrations for most students either just clicks or really doesn’t click. Because they are so different from other mechanical engineering classes, a lot of students struggle with these classes.


In summary, the hardest classes in Mechanical Engineering are one of the calculus or physics courses, thermodynamics, fluid dynamics, and controls/vibrations. Don’t let the courses scare you, though. Remember that engineers often exaggerate things and will unknowingly scare younger engineers that haven’t taken the classes yet. These courses are hard, but not impossible. With hard work, you can get through them. They are simply minor speed bumps on your road to becoming a successful engineer.

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