Feeling rusty with Engineering Fundamentals?
Or worried about passing the FE or PE exam?


LEARNerds gets you back up to speed, by making Engineering Practice
a fun, motivating, ridiculously-simple part of your daily routine.

Every morning at 7AM (EST) we jumpstart your day with a daily Engineering Question,
similar to concepts found on the Fundamentals of Engineering Exam (FE) & Professional Engineering Exam (PE).

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Fire the Cannon - Projectile Motion

You've setup your safety switch. Now to position the cannon!

You have a toy cannon wired up to the safety switch and loaded with a very special cargo. Your target is across the room.

that-was-easy-mentos-cannon.PNG

The target has to be placed 28 meters away. You also know that the initial velocity out of the cannon is
20 m/s. Assume that both the cannon and the target are at the same height.

What angle from the horizontal does the cannon need to be at to make the shot into the target zone?


      Θ = 21.6°
      Θ = 33.5°
      Θ = 42.7°
      Θ = 58.6°
      Cannonballl!!!

Part of the puzzle (of life) is uncovering implicit clues, while deciding what assumptions to make. So comment on any ambiguities you see so others can learn to spot them too!

Make a Safety Switch

You and your best friend about to build the best Rube Goldberg machine ever. You don't want to set it off accidentally, so you two decide to build a two-man safety switch.

staples-950x360.jpg

The two-man safety switch has two buttons which need to pressed at the same time in order to activate your machine. That's nuclear defense security!

You and your friend scrounge up some parts and get ready to build the switch. You are going to use 2 transistors, one for each button. The transistors will act as switches. When both of you close your transistor switch, the circuit should activate the cannon to start the machine!

If you don't remember how transistors work, you can always ask your friend. He reminds you that....

Transistors Review

Open Switch - Inactive

transistor_closed.png

The current flows from the voltage source on the left to the ground on the right. When there is no signal to the middle wire of the transistor, it is an open switch and no current can get from the left side to the right.

Closed Switch - Active

transistor_active.png

When there is a signal on the middle wire of the transistor, such as this pressed button here, then the current is able to move from the left side to the right side of the transistor, and flow through to ground.

Which of the circuits below should you and your friend build?


      A.
      B.
      C.
      D.

Part of the puzzle (of life) is uncovering implicit clues, while deciding what assumptions to make. So comment on any ambiguities you see so others can learn to spot them too!

A Drill Without a Bit

If a tree falls in the woods and no one's around to hear it, does it make a sound?

         Of course it makes a sound! Just because no one is there, doesn't mean it goes away...

         No, it doesn't make a sound. If no one knows it's there, then it might as well not exist...

This question debates common notions of reality. It asks, if something is not perceived at all, then how can it be said to actually exist? Over centuries critical thinkers have debated this question. Classical science is built on the presumption that there exists an external reality. But others argue that there is no way to separate the "observer" from the "observed."

In relation, Torque is also a force that isn't always perceivable and thus can be somewhat unintuitive. For instance, if you add a bit to a drill it's easy to see torque in action. But without a bit, you can place your hand on the end of the drill and yet feel no force except that of friction. So our question for you is... if a drill spins and there is no bit in it, does it have a torque?

Share your answers, questions, or thoughts with us in the comments!

Part of the puzzle (of life) is uncovering implicit clues, while deciding what assumptions to make. So comment on any ambiguities you see so others can learn to spot them too!

Electromagnetic Force in a DC Motor

You might be thinking, "Wait! Isn't this Twerk- I mean Torque-ing week? Why is this a circuits problem?" Well, the principles of torque actually parallel those of electromagnetism quite closely. Check it out below.

Electromagnetism review

When a current I in wire-length moves through a magnetic field B, an electromagnetic force F acts on the current in turn, causing it to move. In the case of a DC motor as shown in the diagram, it will cause the looped wire to rotate.

Use the diagram to assist you in writing the electromagnetic force equation. And given:

I = 2.5 mA,  B = 5 mT (milli-Teslas),  L = 20 cm

Find the Electromagnetic force F. Assume all vectors are perpendicular to each other.

Hint: Try drawing the forces like you would for the torque equation

Part of the puzzle (of life) is uncovering implicit clues, while deciding what assumptions to make. So comment on any ambiguities you see so others can learn to spot them too!

The Drunk Chicken Balancing Act

This image is available under a CC BY license. Attribution: Rice University. Textbook content produced by OpenStax College is licensed under a Creative Commons Attribution 3.0 Unported License.

This image is available under a CC BY license. Attribution: Rice University. Textbook content produced by OpenStax College is licensed under a Creative Commons Attribution 3.0 Unported License.

This poor chicken got its hands on some fermented food. Now it’s inebriated! ... A gust of wind blows on it at an angle of 37° with respect to the horizontal. The horizontal distance from the claw to where the wind force is applied on the chicken is 0.7 cm. 

If the wind’s feeling particularly nice that day, what force should it blow with to help balance this drunken 2.5 kg chicken?


      1 N
      11 N
      14 N
      19 N

Part of the puzzle (of life) is uncovering implicit clues, while deciding what assumptions to make. So comment on any ambiguities you see so others can learn to spot them too!