For example, you could sit an abstract reasoning test without having seen one before and still get a reasonable score. The same is not true of mechanical reasoning, where your score will depend significantly on your knowledge of:
Levers Pulleys Gears Springs Simple Electrical Circuits Tools Arithmetic
You may have come across many of these topics in elementary science and the questions will seem fairly straightforward. If elementary science classes seem like a long time ago, then you’ll need to refresh your memory. This article also covers fault diagnosis questions which are used to select personnel for technical roles where they need to be able to find and repair faults in electronic control systems. The questions in fault diagnosis tests appear rather abstract and require pure logic to solve. This is because when a fault develops in an electronically controlled system, there is often no physical clue as to the cause. In the absence of such a clue, for example, an obviously burned-out component, the only way to diagnose the problem is by a process of logical elimination. Loading… Credit: Psychometric Success If you are taking a mechanical reasoning test as part of the selection process for the emergency services or the military, then the questions will tend to concentrate on principles rather than on making 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. In this case, knowing the principle is not enough; you need to know the formula. You may also be asked some questions about tools and how they are used. If you are taking a test as part of the selection for a craft or apprenticeship job, you should also expect some basic arithmetic questions. These questions approximate the type of reasoning and maths that are needed to estimate materials costs, etc. One final point: many of the questions in mechanical reasoning tests are industry-specific. For example, tests used by the fire service will tend to frame questions in terms of firefighting, whereas tests used to select for an aircraft maintenance job would tend to frame the questions in aviation industry terms. It doesn’t matter if the questions you practice on aren’t specific to the industry you are applying for. It is the substance of the question that is important – the scenario is incidental. No specialist knowledge is required to answer these questions, only an understanding of basic mechanical and physical principles. Mechanical reasoning tests are used to select for a wide range of jobs including the military, police force and fire service, as well as various engineering occupations. These tests are usually of 20–30 minutes duration and contain 20–30 questions that concentrate on the following:
Levers Pulleys Gears Springs Gravity Electricity Magnetism Linear Force Centrifugal Force Centripetal Force Compression Expansion
Levers
A lever consists of a bar that pivots at a fixed point known as the fulcrum. In the example shown, the fulcrum is at the centre of the lever. This lever provides no mechanical advantage and the force needed to lift the weight is equal to the weight itself. This affects the force required in the following way: w x d1 = f x d2 Where:
w = weight d1 = distance from fulcrum to weight f = force needed d2 = distance from the fulcrum to the point where force is applied
In this example, the fulcrum has been moved towards the weight, so that the weight is one metre from the fulcrum. This means that the force can now be applied two metres from the fulcrum. 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)
Example Question
A) 40 lbs B) 50 lbs C) 60 lbs D) 70 lbs However, in mechanical aptitude questions, you may see questions where the fulcrum has been placed closer to the force than the weight. This will mean that a force greater than the weight will be required to lift it. You may see more complex questions involving levers. For example, there may be more than one weight. In this case, you need to work out the force required to lift each weight independently and then add them together to get the total force required.
Pulleys
The pulleys used in this type of question 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 like the ceiling Another pulley
For these questions, you can ignore the effect of friction.
Single Pulley
A) A B) B C) Both require the same force Another way of thinking about this is to divide the weight by the number of sections of rope supporting it, to obtain the force needed to lift it. In A, there is only one section of rope supporting the weight, so 10/1 = 10 kg required to lift the weight. In B, there are two sections of rope supporting the weight, so 10/2 = 5 kg required to lift it.
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. A) A B) B C) Both require the same force A) 100 kg B) 150 kg C) 50 kg D) 60 kg Gears are attached to a rotating shaft turned by an external force, which is not usually illustrated in these types of question. Two gears may be connected by touching each other directly or using a chain or belt. If gears are connected by a chain or belt then they move in the same direction. Meshed gears with an equal number of teeth will turn at the same speed. If they have an unequal number of teeth, then the gear with the fewest teeth will turn faster. To work out how fast one is turning with respect to the other you need to count the teeth.
Springs
A spring is a piece of wire or metal that can be extended or compressed by an external force, but which then returns to its original length when that force is no longer applied.
Spiral coil Leaf springs Torsion springs
Springs are used in many applications including clocks, vehicle suspensions, etc. In the type of questions that you will be asked in mechanical aptitude tests, you can assume that springs behave in a linear way. That is, doubling the force applied will stretch or compress the spring twice as much. You will get access to three PrepPacks of your choice, from a database that covers all the major test providers and employers and tailored profession packs. Example Question A) 10 cm B) 2.5 cm C) 5 cm D) 7.5 cm
Example Questions
A) 1 B) 2 C) 3 D) 4 A) 1 B) 2 C) 3 D) 4 A) 1 B) 2 C) 3 D) 0 These questions are typically straightforward and if you have spent significant time fixing or making things, they won’t present any problems. However, many people under 30 years of age don’t have much practical experience of fixing things or of watching someone else do so. If you feel that this applies to you, then you will need to make some effort to improve your knowledge of everyday tools. You can do this by getting hold of a catalogue for a tool hire company and simply reading through it.
Fractions Decimals Ratios Percentages Averages
These basic mathematical skills are an important aspect of mechanical ability. Making simple calculations based on the information provided and your knowledge of mechanical principles is part of these tests. Some questions may also require you to know some simple formulas. For example: The areas of shapes like rectangles, circles and triangles: A good understanding of forces and energy are also essential, such as:
Kinetic/potential energy Work and power Acceleration Gravity Pressure Friction
Credit: Psychometric Success As modern equipment of all types becomes more dependent on electronic control systems (and, arguably, more complex), the ability to approach problems logically to find the cause of the fault is increasingly important. This type of test is used extensively to select technical and maintenance personnel, as well as to select for artificer (technical) roles within the armed forces. For example, an aircraft technician. This type of test usually forms part of a test battery in which verbal reasoning and numerical reasoning also feature. No specialised knowledge is required to answer fault diagnosis questions (unlike mechanical reasoning). Only when you are happy that you understand how these questions work should you attempt the practice tests. Remember that the object is to work systematically through the questions and avoid mistakes.
Example Question
There are two components to this question: Each of the switches acts to alter the input before the next switch in the series. The first switch (diamond symbol) inverts inputs one and two. That is, if the input is on, it is turned off and if it is off it is turned on. The other switches act in a similar way as detailed in the grid. If a switch is not working then it does not affect the input which passes through unchanged. In this example flowchart, all of the inputs (numbered 1, 2, 3, 4) are on. When these inputs pass through the first switch 1 & 3 are inverted (i.e. switched off). These modified inputs (1 = off, 2 = on, 3 = off, 4 = on) then pass through the second switch. The second switch inverts inputs 3 & 4 which gives (1 = off, 2 = on, 3 = on, 4 = off). These modified inputs (1 = off, 2 = on, 3 = on, 4 = off) then pass through the third switch. The third switch should invert inputs 2 & 4, giving (1 = off, 2 = off, 3 = on, 4 = on). However, the third switch is not working so the output from switch two is not changed. The answer to this question is, therefore, C, because switch type C is at fault. Credit: Psychometric Success A suggested list of topics to revise includes (but is not limited to):
Levers Gears Pulleys Springs Screws Acceleration Gravity Clamps Shafts Pressure Friction Weights Volumes Conveyor belts Kinetic and potential energy Balancing scales Simple electrical circuits Applied maths Magnetism Mirrors and reflection
Take the time to understand in your own mind what problems are solved by these mechanical techniques, how they work and how they are applied in the real world. Learn from your practical experience. Preparing for mechanical reasoning tests does not have to be entirely theoretical. If you enjoy working with your hands, practise taking things apart to understand how they work. Fix things. Build things. Try ideas out practically and see what you learn from doing so. Find opportunities to work with tools and equipment, read technical user manuals, anything that familiarises you with the mechanical mindset and builds your knowledge. Practising example aptitude questions is also important. Make sure that you work through some practice tests (we recommend JobTestPrep’s mechanical tests), to ensure you understand how to solve the questions. Credit: Psychometric Success
