VERY HARD Mechanical Comprehension Test - I dare you to try this and not fail

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TheFarmerLad
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If you wanna try it here's the link: https://www.shldirect.com/en/practice-tests/

There are 20 questions (screenshots below), I've put my answers up but can't get above 70%. There don't appear to be any answers online either..

EDIT; some answers have since changed, all updates are now currently on this thread; https://www.thestudentroom.co.uk/sho...4#post87979984
Last edited by TheFarmerLad; 1 year ago
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TheFarmerLad
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cont
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TheFarmerLad
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My answers chronologically:

D
D
B
C
A
B
A
A
B
C
C
C
D
D
B
C
C
A
B
B
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TheFarmerLad
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bump
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TheFarmerLad
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any help pls i'd be so grateful
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trapking
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(Original post by TheFarmerLad)
any help pls i'd be so grateful
I just did it but it doesn't tell me what my score is?

I enjoyed doing this
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TheFarmerLad
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(Original post by trapking)
I just did it but it doesn't tell me what my score is?

I enjoyed doing this
What answers did you get man? I've since redone it and got 20 so can help you with your answers if you'd like!
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0le
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My intepretations:
Question 1: I don't understand the picture whatsoever.They should label the picture to make it clearer. It is just a hydrostatics question though. This is arguably the worst diagram for a hydrostatics question I have ever come across.

Question 2: I presume it is D because Laplace pressure is likely to be larger with greater curvature. Effectively the pressure inside the balloon is equivalent to the pressure outside + the surface tension forces. But if the temperature of the balloon was very low, then the balloon would be a solid object right, would it matter then?

Question 4: Mechanisms questions. Don't know anything about them. Studied them in first year for a few weeks. Bound to be some simple formula to calculate it though. I'm guessing it is C, because turning the small screw twice would turn the big screw once. This is because there are say 100 teeth on the big screw but only 50 teeth on the small. So you would need to go through 2x50 teeth to get through all the teeth (one revolution) of the big screw. So if the small screw turns 6 times, it should make the big screw turn 3.

Question 5: Don't know mechanisms. I would guess A but I don't know why.

Question 6: Again don't know mechanisms. Guess B. Looks like turning the sprocket C clockwise turns the adjacent gears anti-clockwise. This means handle 2 goes anti-clockwise. Sprocket B moves anti-clockwise and therefore pulls sprocket A clockwise. So handle 1 goes clockwise.

Question 7: Don't know much about light. Why is this related to mechanical engineering, how many students are actually taught about optics?

Question 9: Don't know. Seems like a physics question although there are some youtube videos which I remember explaining this. Probably related to angular momentum and rotation. Surely you need to know the mass of the objects though?

Question 10: Assume the hook and loop system is metal so it cannot stretch. It cannot reach point B. If you placed it at A or D, there would be no slack in the chain, so it would not let the door open. It must therefore be C.

Question 13: Yay another mechanism question...I think it is between point Y and Z but I can't say which is furthest. The picture is also rubbish.

Question 15: I would have guessed B. You place the belt in the middle so the moment arm is zero.

Question 19: No idea and to be honest I don't care much for mechanisms. Not sure why L would move if it is free to rotate on its own.

Question 20: ANOTHER mechanisms question. Feck knows.

Some of these questions are also problematic.
Question 3: With the water flow it seems to assume the flow is subsonic. If the flow is subsonic then the velocity greatest at B. But the total pressure is also the same within the whole pipe if you ignore frictional losses and it doesn't explicitly state whether you are dealing with static pressure (although normally it is presumed).

Question 8: Terrible question. I intepreted this as the magnets attracting in the vertical direction. Therefore it can't be A and C because from A-Level Physics, the same poles cannot attract. You are left with B and D but you can't actually pick which one because you do not know how they align with magnet 1. I guess you are meant to "assume" the magent 1 is orientated the same in row 2 as in row 1...so the answer is D. But from what others have said, they seem to want the magnets to placed so they attract horizontally, so in that case it would be A. The diagram should be clearer.

Question 11: WTF is a downspout? I'm guessing it is a pipe. But you have to assume here the pipes are the same, so the friction losses are the same. You also have to assume the angles of the pipes are relative to the same vertical plane. The water will slide due to a component of gravity. To me it seems largest for house C and smallest for house D.

Question 12: Again, you have to assume the bottom of the pan has the same surface. Normally you place objects in the central potion of a flame where ti is hottest, so guessing C here.

Question 14: seems made up to me. How can you know this looking at those **** pictures and not having a clue how the boundary layer develops on any of them? You can guess it won't be A or B because perhaps you can say the profile drag is largest. But how the feck do you know whether it is C or D? Maybe its a mechanics type question that ignores aero affects but again, the question doesn't say...

Question 16: Another **** picture. Like what? Where is the table or ground relative to the paper? Is the paper already blowing in the wind? lol? Assume the paper is on the table. Now put the ball at point C. A wake will form behind the ball which will limit how much of the paper will frail in the wind. Can't explain the physics though.

Question 17: The trailer won't move. Just because you turn the steering wheel doesn't mean the car will move. So you are assuming that you also put your foot on the gas. I also don't know the relationship between turning a steering wheel clockwise/anti-clockwise and how that first moves the car.

Question 18. Again, you have to assume everything about the slides is the same apart from the change in dimensions. But it doesn't state this...Postion 1 seems more logical to reduce form drag. So that leaves you with picking either A or B. I personally then would guess A. It has a greater component of gravity acting on the person to overcome friction.

Conclusions:
Too much emphasis on mechanisms whether its gears or screws or whatever. Little emphasis on fluid dynamics. One question on thermodynamics, none on electronics, control systems, or mathematics. Lots of **** diagrams. Lots of assumptions need to be made which aren't stated - a cardinal sin for any engineer. Rubbish test, as are nearly all psychometric tests.

(Original post by TheFarmerLad)
My answers chronologically:

....
Could you please explain your reasoning, particularly for the mechanisms questions and also question 11.

Also OP, next time, please label properly your attachments. It was very difficult to respond to your question.
Last edited by 0le; 1 year ago
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Smack
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(Original post by 0le)
Could you please explain your reasoning, particularly for ... question 11.
I'm going with b (D will have the greatest flow; C the least) because house D will catch more water as it presumably has a larger surface area due to the roof being less steep.

I certainly agree it's a hard test - I wouldn't do good at it! However keep in mind that it is a mechanical comprehension test, it's not designed to test everything from the uni syllabus. I could see this as being a useful test for many mechanical or related engineering jobs in industry (although obviously not used on its own) as it tests your fundamental understanding of how mechanisms and machines work.

Also, thanks for taking the time to separate the questions out.
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0le
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(Original post by Smack)
I'm going with b (D will have the greatest flow; C the least) because house D will catch more water as it presumably has a larger surface area due to the roof being less steep.

I certainly agree it's a hard test - I wouldn't do good at it! However keep in mind that it is a mechanical comprehension test, it's not designed to test everything from the uni syllabus. I could see this as being a useful test for many mechanical or related engineering jobs in industry (although obviously not used on its own) as it tests your fundamental understanding of how mechanisms and machines work.

Also, thanks for taking the time to separate the questions out.
Volume flow rate = AV where A is the cross sectional area and V is the velocity. This question still just confuses me a lot. I feel that just because the roof has a greater surface area, the flow of water through the pipe will still be greater in C because the pipe diameters all look the same. Yes, I agree that D will catch more water" but from the picture it seems like it is constantly raining? What if D has a flat horizontal roof that had a large surface area for example - very little water would fall into the pipe so the flow rate through that pipe would be minimal?

Just a stupid question if you ask me. Oh well
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Smack
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(Original post by 0le)
Volume flow rate = AV where A is the cross sectional area and V is the velocity. This question still just confuses me a lot. I feel that just because the roof has a greater surface area, the flow of water through the pipe will still be greater in C because the pipe diameters all look the same. Yes, I agree that D will catch more water" but from the picture it seems like it is constantly raining? What if D has a flat horizontal roof that had a large surface area for example - very little water would fall into the pipe so the flow rate through that pipe would be minimal?

Just a stupid question if you ask me. Oh well
I think you're over complicating the question a bit. It's not about answer an equation (and the equation you've mentioned doesn't necessarily apply in this instance as the water flow almost certainly full the entire cross section downpipe). If D had a flat roof then it would catch even more water and its flow rate would likely be even higher.

The biggest consideration in this instance is simply the amount of water available to flow through the pipe. The question also helps us slightly, because it we apply this theory we would therefore expect C to have the lowest flow as it'll collect the least amount of water, and there is an answer that satisfies this exactly.
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0le
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(Original post by Smack)
I think you're over complicating the question a bit. It's not about answer an equation (and the equation you've mentioned doesn't necessarily apply in this instance as the water flow almost certainly full the entire cross section downpipe). If D had a flat roof then it would catch even more water and its flow rate would likely be even higher.

The biggest consideration in this instance is simply the amount of water available to flow through the pipe. The question also helps us slightly, because it we apply this theory we would therefore expect C to have the lowest flow as it'll collect the least amount of water, and there is an answer that satisfies this exactly.
Personally I don't think the question makes much sense and I don't agree with the reasoning.

You can observe a simpler example by looking at experiments where droplets impinge on surfaces. On a flat surface, after the initial collision is over, the droplet just doesn't move. It loses all its energy after a certain period of time. However if the surface is at an angle, the droplet could slide along the surface.

Now if you attach a pipe to the end of the surface, which case will have the droplet of water go through the pipe? Well the one where the surface is angled into the direction of the pipe. Therefore this will have a flow of water through it. The flat surface won't lead to the single droplet going through the pipe, so the pipe has no flow through it

That is how I visualise the example anyway.

I am aware the answers don't give that answer, which is why I disagree with the question. I really detest questions like this (and others in the test). It just serves to rile me up!
Last edited by 0le; 1 year ago
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oliphint4
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I can't believe you didn't get more of a response on this thread. All the companies in my area are using these SHL tests for hiring. Of their current practice test--a bit different than what you have below, I am getting two wrong and can NOT figure it out. You have to create a new log in each time in order to retake the test, so it gets a bit cumbersome. Of course, these aren't the questions which actually get asked on the version administered by the companies. Drives me nuts that I can't figure out what I'm doing wrong. I'm pretty mechanically inclined.
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TheFarmerLad
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(Original post by oliphint4)
I can't believe you didn't get more of a response on this thread. All the companies in my area are using these SHL tests for hiring. Of their current practice test--a bit different than what you have below, I am getting two wrong and can NOT figure it out. You have to create a new log in each time in order to retake the test, so it gets a bit cumbersome. Of course, these aren't the questions which actually get asked on the version administered by the companies. Drives me nuts that I can't figure out what I'm doing wrong. I'm pretty mechanically inclined.
Which companies?
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TheFarmerLad
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FYI to all new in have since completed this so if you're stuck I'll attempt to lend a hand. Can brainstorm other similar tests too if so desired
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TheYear200
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I can't seem to get past 70% i sit for my final aptitude test friday. Any hints on how to get higher than 70% would be a bonus :-)
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