Mechanical Reasoning: Preparation, Practice & Example Test Questions

Mechanical Reasoning Tests

What Are Mechanical Reasoning Tests?

Mechanical reasoning tests evaluate your knowledge and understanding of clear mechanical and physical concepts, visual and spatial relations, as well as knowledge of tools.

These tests do not measure your innate cognitive abilities.

Your performance on the test is heavily dependent on your previous knowledge of concepts such as gravity; how simple machines such as levers, pulleys, gears, springs and electrical circuits work; and your understanding of how objects can be moved and organised in space.

When Are Mechanical Reasoning Tests Used?

You can expect to be asked to complete a mechanical aptitude test if you are applying to roles in emergency services (e.g. firefighting department), the military, some technical positions, or if you are applying for a craft.

In the emergency services and the military, Mechanical Reasoning tests often focus more on concepts and principles (e.g. which of the presented levers is more efficient) rather than making calculations and computations.

For craft and technical roles, you will often be required to do calculations (e.g. calculating the forces required to move a lever).

In this case, the mere understanding of the concept won’t be enough, and you will need to know the formula.

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Fault Diagnosis

At the end of this article, we are adding a section on Fault Diagnosis.

Fault Diagnosis questions are frequently seen in mechanical assessments for technical roles where the candidates will be required to allocate and fix faults in electronic control systems.

These questions are usually abstract in nature and require pure logic to answer.

The questions are formulated in such way simply because when a fault occurs in an electronically controlled system, there is usually no physical/visual evidence of what the underlying reason might be (e.g. burned-out wire).

The only way to uncover the reason is to eliminate potential causes.

These types of questions are used primarily in the selection of technical and maintenance personnel within the armed forces where the capacity to address issues logically to find the cause of the fault is of immense importance.

What to expect on a Mechanical Aptitude Test

There are various ways to structure an aptitude test. In most of the cases, though, mechanical aptitude assessments come in the form of multiple-choice questions, where test takers are required to analyse a picture or diagram of an object and pick the right answer.

A mechanical aptitude test typically covers mechanical reasoning, visual/spatial relations, gravity and/or tool knowledge. In the below table, you can find the types of questions to expect:

Here’s a breakdown of each test area.

Example Mechanical Reasoning Questions And Answers

Mechanical reasoning questions aim at measuring candidates’ previous knowledge of physical and mechanical concepts to evaluate their suitability for roles in military, emergency services and technical departments.

While the tests require some foundational understanding of basic principles in mechanics and physics, they don’t really need any previous specialised knowledge to solve.

The assessments usually take 20-30 minutes to complete, and are comprised of 20-30 questions focusing on wheel and axle, levers, pulleys, gears, springs and simple electrical circuits.

Levers

A lever is composed of a bar, with axes at a fixed point referred to as the fulcrum. In the below drawing, the fulcrum is at the mid of the lever. Accordingly, this lever is providing no mechanical benefit, and the force needed to lift the weight is equivalent to the weight itself.

However, if you want to lift a weight heavier than the force being applied, you will need to move the fulcrum closer to the weight you want to lift. The formula that regulates this relationship is as follows:

w x d1 = f x d2

Where:

w = weight
f = force needed
d1 = distance from fulcrum to weight
d2 = distance from fulcrum to point where force is applied

As illustrated below, when the fulcrum was shifted toward the weight so the weight is 1 meter from the fulcrum while the force being applied is 2 meters away from the fulcrum, the force is reduced by 50 percent.

This has been calculated by rearranging the formula as below:

w x d1 = f x d2 can be rearranged to f = (w x d1)/d2
f = (10 x 1)/2 (10/2 is the same as 5/1, the force required is 5 Kg)

Below are some more example questions with increasing complexity along with their answers:

Which of the two levers require less force (in the direction indicated by the arrow) to
lift the box?

Answer

A – Lever A requires less force to move the 50 pounds. Whenever a force is applied to a point far from the fulcrum, less force is required to achieve the same amount of work. Both levers must push the same weight (i.e., move 50 pounds of load); however, Lever A will do so more easily because it is much further from the point of force to the fulcrum on Lever A than on Lever B.

In practice, levers are used to minimize the forces required to lift a heavy object. However, in a mechanical reasoning assessment, you can expect to get questions where the fulcrum has been placed far from the weight.

This will mean the force you need to apply to lift the object will be greater than the weight you are trying to lift.

Below is a bit more complex question involving multiple weights. In similar cases, you will need to compute the force required to lift each weight separately and then add them together to get the total force required to move them both.

How much force is required to lift the weights?

A) 25lbs   B) 35lbs   C) 40lbs   D) 45lbs

Answer

B – 35lbs is needed to lift the weight. It can be calculated like this:

f = (w1 x d1) + (w1a x d1a)/d2 f = (20 x 10) + (30 x 5)/10
f = (200 + 150)/10
f = 35 lbs

Wheel and Axle

A wheel and axle is considered one form of levers, and it is composed of a large wheel attached to a smaller shaft (axle), which permits the wheel to rotate/move. The wheel and axle provide a way to generate mechanical advantage.

Through a small force applied to the periphery of the large wheel, one can move a larger load attached to the axle.

The formula you need to answer wheel and axle questions is:

IMA (Ideal Mechanical Advantage) = R/r

R is the radius of the wheel r is the radius of the axle, and the center of the axle here acts as the fulcrum.

Pulleys

Pulleys consist of a grooved wheel and a block that holds it. A rope runs in the groove around the wheel, and one end will be attached to either: a weight, a fixed object such as the ceiling or to another pulley.

The questions that include pulley require candidates to compute the forces required to move the weights. In real life, friction between the rope and the wheel might slightly change the force, but for the purposes of the mechanical tests, these friction factors are ignored.

Questions on pulleys can come in varied complexity, including questions involving single, double or even multiple pulleys.

If both boxes are of the same weight, which one requires the least force to move?

 

A) Left Box    B) Right Box    C) Both require the same force

 

Answer

B – Weight B requires less force than A requires.

Single pulley questions are usually straightforward. If the pulley is fixed, then the force required is equal to the weight.

However, if the pulley moves with the weight, then the force needed is equal to half of the weight. Another way of remembering it is by dividing the weight provided by the number of sections of rope supporting it to obtain the force needed to lift it.

In the above figure, the box’s weight was 10Kgs. In A, there is only one section of rope supporting the weight, so 10/1 = 10 Kg of force is required to lift the weight. In figure B, there are two sections of rope supporting the weight, so 10/2 = 5 Kg of force is needed.

Double Pulleys

There are two possible ways that two pulleys can be used. Either one pulley can be attached to the weight or neither of them can be.

How much weight is required to move the box below?

A)10    B) 5    C) 2.5    D) 1.25

Answer

A – Weight A requires a force equivalent to 5 Kgs. Again, remember to apply the same concept of dividing the weight by the number of sections of rope supporting it to get the force needed to lift the weight.

 

Multiple Pulleys

How much force is required to move the weight?

A) 10 Kg    B) 5 Kg    C) 2.5 Kg    D) 1.25 Kg

Answer

C – Since the weight is 10 Kg and there are 4 sections of rope supporting it, then by dividing 10 by 4, you will get 2.5 Kg. In all cases, just divide the weight by the number of sections of rope supporting it to get the force needed to lift the weight.

Gears

A gear is a wheel that has teeth throughout the outer edge. The gear is the mechanism that makes clocks move.

When the teeth of two gears fit together and one gear turns, the other gear starts to turn as well, but in the other direction.

Also, you should expect if two gears are presented equal in size, they would have the same number of teeth. When they both move, they will be moving at exactly the same speed and making the same number or rotations.

However, if two gears are of different size yet moving at the same speed, you should expect the smaller gear to do more rotations.

Two gears may be connected directly by touching each other like in a watch or by means of a chain or belt, as in the case of the bicycle.

If two gears are connected by a chain or belt, then they move in the same direction. If the gears are touching (meshed), then adjacent gears move in opposite directions.

In the below figure, the first and third gear will turn in the same direction.

Remember, when there are an odd number of meshed gears, the last gear will always turn in the same direction as the first one.

 

Question: If the 1st gear is moving inward, in which direction the 4th gear is moving?

A) Inwards    B) Outwards

Answer: Outwards

Springs

A spring is piece of wire or metal that can be stretched or compressed by applying force. However, it restores its original length once this force is removed.

There are many different types of spring, including spiral coil, leaf springs and torsion springs, and they have several applications including clocks and car suspension systems.

For the sake of the mechanical aptitude assessment, you should expect to be asked questions about springs behaving in a linear fashion. In other words, you should assume that doubling the fore applied to the springs will cause it to be compressed twice as much.

You can also expect questions asking about springs arranged in parallel or in series. When arranged in series, the force applied impacts both springs equally. When arranged in parallel, the force applied gets divided equally between both springs. This is called Hooke’s Law.

For example, if a force of 1 Kg compresses the springs in series by 10cm, what will be the total distance the springs in parallel are compressed?

A) 10 cms    B) 2.5 cms    C) 5 cms    D) 7.5 cms

Answer

C – The total force will be divided equally between the two springs that are arranged in parallel. Given we will assume a linear relationship between force and distance, since the force is divided in half, the distance moved will also be reduced by 50 percent. If the springs in series were moved by10 cms, therefore, the springs in parallel will be moved only by 5 cms.

Gravity

Gravity is the force by which a planet or other body draws objects toward its center, and it is an important concept that you must understand to be able to answer many mechanical aptitude assessment questions.

A full discussion on gravitational forces is beyond the scope of this article (as well as what you need to know to pass in a mechanical aptitude assessment). Instead, you only need to know a three key facts:

  • Gravitational force is always downward.
  • It creates resistance for any object moving upward
  • The force of gravity applied on every object is the same, regardless of the object’s weight, size, shape, etc. and accordingly, any falling object that is moving only by the force of gravity (i.e. in free fall situation) will move at the same rate toward a resting point.

Questions on gravity in mechanical aptitude assessments don’t usually ask about the rate of falling, but rather evaluate your understanding about those three concepts. Below are two examples of questions you can expect to see:

Electricity

Questions on electricity usually take the form of simple circuit diagrams.

These diagrams are usually limited to presenting the power source, switches, loads (usually bulbs) and the path of the wiring. To answer the questions around simple circuits, you need a basic knowledge of how electricity flows around a circuit.

Example Question

In a parallel circuit, if one of the light bulbs burns out, the rest:

A) stop the flow of electricity
B) can still light up
C) will go out
D) of the light bulbs burn out also

 

What will happen if one light bulb is removed from this circuit?

A) The other bulbs will go out.
B) The other bulbs will get brighter.
C) The other bulbs will get dimmer
D) The battery will become stronger

 

If bulb 1 is removed, how many bulbs will light up when the switch is closed?

A) 1    B) 2    C) 3    D) 0

Answer

B – Only bulbs 3 and 4 will light up.

Basic Numerical Skills and Formulae to Remember

Some of the assessment questions you might see require previous understanding of basic mathematics, fractions, decimals, ratios, percentages and averages. These basic numerical skills are a key element of mechanical aptitude assessments for jobs that need making simple calculations on the basis of the data provided.

Additionally, some questions may test your knowledge about simple formulae such as surface areas of shapes:

and some simple geometry such as Pythagoras Theory.

For example, calculate the length of c when a=4 and b=3

Answer = 5

Tools

Mechanical aptitude tests vary significantly in difficulty as well as the types of questions posed based on the jobs you are applying to and the knowledge required to perform these jobs.

For example, if you are taking a mechanical aptitude test as part of the selection process for the emergency services or the military, the questions will tend to concentrate on principles rather than on making the calculations.

For example, you may be shown three diagrams of a lever and asked which one is the most efficient.

If, however, you are taking a test for a craft or technical job, you may be expected to calculate the actual force required to move a particular lever, or the distance a spring will move in parallel and series setting. In this case, knowing the principle is not enough.

You need to know the formula as well.

You may also be asked some questions around tools and how they are used. These questions are again straightforward. If you have spent significant time fixing or making things, they shouldn’t present a challenge.

Tool knowledge questions assess your ability to both identify and/or enumerate the uses for common types of tools such as hammers, wrenches and pliers.

Having familiarity with a wide range of tools is your best preparation for answering these types of questions.

If you do not have experience with some tools, though, you might consider making some effort to improve your knowledge of these everyday tools through getting hold of a catalog for a tool hire company and reading through it.

Examples:

What is the name of this tool?

A. Pliers B. Hammer    C. Sledge    D. Mallet

If you don’t know the answer because you didn’t see this tool before, you can think of using elimination technique.

The other type of questions around tools is the tool usage questions. Below is an example of how these types of questions could be presented in a mechanical aptitude assessment:

Which tool is best used for tightening and loosening hex-head bolts?

Tool A:

Tool B:

A. Tool A  B. Tool B    C. Both    D. Neither

The answer is B. If you already knew both tools, then responding to this question would be straightforward. However, if you don’t have this knowledge, you could leverage some of the principles of mechanical reasoning to answer the question.

To elaborate, as the name implies, a hex-head bolt has six sides, as in a hexagon. Sketching the bolt (or even visualizing it) can help you determine what kind of tool is needed to tighten or loosen it. You could figure out that you only need to grasp two sides of the bolt to turn it.

Both Tool A and Tool B appear capable of grasping two sides of a bolt, and hence you can’t rely on this only to exclude one of them.

However, you could also observe that Tool B has a wheel and axle that probably help adjust the width of the opening.

Thus, Tool B could be adjusted to fit bolts of various sizes and remain fixed at the appropriate width while it is used. Tool A, however, would require applying constant manual pressure to keep the appropriate width to match the bolt. Thus, Tool B would be better than Tool A for the specified purpose.

Visual and Spatial Relations

Assessment questions related to visual/spatial relations usually ask you to identify objects by recognizing pattern, shapes and/or spatial orientation.

Usually, more than on aspect of an object is engineered at the same question, so you should carefully consider more than one characteristic of the object presented to correctly answer the question.

In this section, we will show typical types of visual and spatial relations questions, including: hidden figure, spatial views, block counting and paper folding questions.

Hidden Figure

In these questions, you are required to find a target shape that is embedded (hidden) within another figure containing a variety of other shapes, lines and patterns. See the below example asking about determining the figure that contains a target shape.

The answer is A.

This example demonstrates important features of the hidden figure type of question. As you will see, behind being hidden in a group of similar shapes, the spatial orientation of the target figure has changed, and it was masked by dividing it by a line in the middle.

Spatial Views

In these questions, you are typically asked to put together a 3D shape through looking at some 2D perspectives. The below is an example for these types of questions:

The answer is A

When you try to answer spatial views questions, start with visualizing the shape in your mind based on the givens you have, and then try to map your mental image to the answers provided.

In case your visualized figure didn’t match any of the available options, identify a unique characteristic (e.g., shape) of one of the provided pieces and try to locate that same characteristic in one of the options. In this example, it is the Trapezoid.

Block Counting

In these questions, you are required to understand a picture of blocks in various configurations.

You may be asked to count the total number of blocks or detect how many blocks are touching a certain block. In both types of questions, you must consider that some blocks may be hidden from view.

The answer to the first question is B (13 blocks). You should count for the hidden block under the block X. For the second question, the answer is B (two blocks) because only the block on top of and to the right side of block Z directly in contact with it.

Paper Folding

The last section here is the paper folding questions, in which you are required to put together a 3D object by mentally folding a paper cutout of the object.

In the below question, you are asked to fold this paper to build a house and determine which house the paper can create.

The answer is B, because whether you are folding it upward or downward, you must have a colored wall and a colored roof. However, you can’t have them at the same side.

 

Fault Diagnosis Questions

Fault Diagnosis assessments are used during the selection process of technical personnel who need to be able to find and repair faults in electronic and mechanical systems using deductive-logical thinking.

With the increase of reliance on complex electronic control systems, logical reasoning to diagnose faults in systems is becoming critical for technical and maintenance jobs. Unlike the mechanical aptitude, no previous knowledge is required to answer these fault diagnosis questions.

In these assessments, questions can come in the below format when there are four symbols displayed above a tube. The order of the symbols is changed within the tube according to a certain logic.

That’s why you can see the same four symbols in a different order below the tube. Your task is to identify through which of the branches the symbols went on their way through the tube.

Answer is 3241.

This assessment is timed, and you need to answer as many questions correctly as possible. The complexity of the questions also starts to increase as you progress further.

This can be in the form of adding a sequence below the symbols at the top side of the tube, and you will be required to rearrange the symbols according to this new sequence before determining the correct answer.

The answer is 2341 because when you rearrange the pattern on the top, you first get the below arrangement:

To achieve the arrangement at the bottom of the tube, you will need to arrange them as 2 (triangle), 3 (circle), 4 (square), and 1 (cross)

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