Try this quiz: Which truck is in motion?

by Mark Bennett

July 28, 2023

Try this quiz: Which truck is in motion?
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Quizzes, puzzles and riddles are great fun to attempt and also give us a chance to exercise "our grey matter".

In the quiz below, you will be presented with a a challenge that could be defined as having physics at its heart - but don't be scared, it's not really complicated. In fact, the quiz describes a situation that we have all probably experienced numerous times in real life!

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The truck quiz: test your deductive abilities

The truck quiz: test your deductive abilities

In the image, 3 trucks labelled A, B, C respectively are depicted. The trucks and loads they are carrying are identical in size and weight, so don't worry about those variables. To help you figure out the puzzle, let's imagine that the vehicles are all carrying a large amount of liquid.

The question to be answered is the following: based on what you can see in the trucks' tanks, which of these is actually in motion?

Look closely at the image and especially at the liquid in the three tanks - then give your reasoned answer...

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Tackling the puzzle

Tackling the puzzle

The beauty of many puzzles is the fact that they are applicable to our prior knowledge and the reasoning required comes partly from logic and partly from one's own life experience.

Small tip: if you have ever driven heavy vehicles such as trucks, you will certainly have an advantage in giving the right answer.

But take your time and try to come to a reasoned answer.

The answer

The answer

Ghislain SILLAUME/Flickr

Are you sure you have the right answer? We assure you that the solution to this puzzle is far from obvious: if you want, take a few more moments...

And the correct answer is... all 3 trucks are in motion! Yes, that's right and here's why: all the trucks have their contents "postioned" as they are depicted due to different kinds of acceleration!

Truck A has negative acceleration as it is braking: in this case, the liquid moves towards the front of the tank.
Truck B has no acceleration, i.e. it is at a constant speed: for example, it is traveling at a constant, steady speed on a motorway. Note: the liquid level in truck B is not completely flat (which it would be if the truck was not moving).
Truck C has positive acceleration, i.e. its speed is increasing: the liquid moves to the rear part of the tank thanks to inertia.

Did you get the right answer?

Source:

Image credit: Pixabay

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