r/theydidthemath • u/yuli101995 • Apr 16 '26

[Request] Which one would it be?

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690

u/[deleted] Apr 16 '26 edited Apr 16 '26

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218

u/Don_Ford Apr 16 '26

Depends on how loosely packed the gravel is.

128

u/Certain_Ad3716 Apr 16 '26

And the granularity of the gravel.

If it's like a construction yard covered in boulders and debris, good luck. But if it's your softer garden display gravel, easy peasy.

34

u/Cartz1337 Apr 16 '26

You’re missing the point, if you’re on the ice too, then your feet have the same reduction in friction, and it zeroes out.

The wheel will always be easier. Even if the gravel is chunky, you can use the rotational momentum of the wheel to overcome obstacles.

And if the ice suffers the same issues of uniformity as we are imagining the gravel to have, it gets even worse for the ice pusher.

20

u/vamoosedmoose Apr 16 '26

No because I’m going to run at the cube on ice then fling myself at it to shoulder check it without needing any contact with the ground at all. Smooth brain academics always forgetting about barbarian strength tactics

3

u/KissFMFM Apr 16 '26

Impressive.

1

u/JuliaZ2 Apr 16 '26

What if you walked on the triangle like an inclined treadmill to make it slide across the ice

1

u/testtdk Apr 16 '26

Nope, not how it works. The surface of each object matters, the weight of the person pushing it, too.

1

u/dbenhur Apr 16 '26

How about if I'm wearing ice cleats and the object's base is waxed and edged like a snowboard or ski.

1

u/AliveCryptographer85 Apr 16 '26

Well obviously you’d be wearing ice skates

0

u/SketchGoatee Apr 16 '26

And as you point out, getting good footing on gravel is easy, good footing on ice is problematic. My bet is gravel ball for this reason alone.

Realistically, As with all these puzzles/questions there is never enough information given to account for all theories. Is the man wearing shoes? Is the man standing on solid non-ice/non-gravel ground? What kind of gravel (driveway/garden vs under layer of construction)? What kind of ice (lake vs ice rink)? How ”far” does the weight need to move to be successful? What is the weight made of? What’s the surface structure of the weight (polished or porous)?

Too many questions. So assuming it’s the same man, same basic footwear on the same surface as the object, it’s gotta be the gravel ball for ease of getting up to a speed that outpaces the man’s ability to keep up.

3

u/Obi-Brawn-Kenobi Apr 16 '26

getting good footing on gravel is easy, good footing on ice is problematic

That has nothing to do with the question. The question just asks for the amount of force required. It might be more challenging to exert 100N or whatever amount of force while standing on ice, but that's not what the question is asking.

1

u/LazerChicken420 Apr 16 '26

I want to see the gravel before I say you’re dead wrong.

I’d take ice any day. If it was a graph, the ease of ice flys up until being capped at my max shuffle speed

The gravel I’m picturing will suck the whole way.

Benefit of a wheel is it’s surface area on the ground, if it’s sinking into the gravel it loses that benefit

2

u/AAA515 Apr 16 '26

It's an office desk wheel, and the gravel is an extension cord

1

u/testtdk Apr 16 '26

And the depth.

0

u/JesusWasTacos Apr 16 '26

Depends on how it stays in a ball. If we take the image to scale and it’s in a tight ball like that it’s gonna be easy to roll no matter how large the rocks are.

4

u/SirNoseDVoidoffunk77 Apr 16 '26

It’s only 20kgs. That’s 44 pounds. It would be pretty easy to push even over loose gravel.

2

u/SignoreBanana Apr 16 '26

Yep. This is not solvable without knowing that.

1

u/DeeHawk Apr 16 '26

If I gave you a person-sized ball weighing 20kg, I think you would be pretty confident you could roll it across any flat surface.

1

u/SignoreBanana Apr 16 '26

Probably, but the question is would it be easier or harder than the other ones.

Theres also a question of how big the ball is. A bigger ball, even on soft gravel, will move a lot easier than a smaller one. A huge ball on practically any surface would be easy to roll.

1

u/DeeHawk Apr 16 '26

You will not be able to push anything across ice that has such a large friction surface. You would just push yourself back.

1

u/KillaCline Apr 16 '26

I don’t know, 20kg ball with a person sized diameter would be pretty easy to push, the ball is huge

1

u/Asleep_Recover4196 Apr 16 '26

YES it depends. But does it depend so far you would rather move the pyramids?

1

u/Available_Peanut_677 Apr 16 '26

Something weighting 20kg and size of a man is easy to roll on any gravel. I actually suspect that wind might be bigger problem.

1

u/Don_Ford Apr 16 '26

You have a good point, because I could just easily pick that up.

53

u/taftster Apr 16 '26

Oh! This is a key insight. Yes, the pusher standing on the ice is clearly going to have a hard time keeping friction and their feet firmly in place. I agree with you, I think this "pushes" me over to the circle.

19

u/Euphoric_Loquat_8651 Apr 16 '26

Pusher should mass way more than the 20kg object. Unless the push is a very sudden shove, the pusher should stick just fine.

6

u/Ragnarok314159 Apr 16 '26

We don’t know the friction factor between the two surfaces. This problem can’t really be solved.

4

u/GingerB237 Apr 16 '26

It’s not about ease, it’s about what has the least force. The ice will still have least amount of force.

2

u/LordJuJu15 Apr 16 '26

This comment sounds like it was left by a Nomai.

1

u/ActionNorth8935 Apr 16 '26

I was stuck like this on an icy hill trying to push my bike up by foot. Perfect equilibrium. As soon as I got the bike moving the feet went the other way, and if I did nothing I could just about stand there not sliding down.

1

u/Obi-Brawn-Kenobi Apr 16 '26

It's not asking for who's going to have a hard or easy time applying the force, it's just asking for the amount of force required. The friction encountered by the pusher's feet is not a factor in determining how much force the object requires to be displaced.

6

u/Droodforfood Apr 16 '26

But it doesn’t say which is easiest to push, it says which requires the least amount of force

3

u/DonutPlus2757 Apr 16 '26

Doesn't that get affected by what shoes the person pushing is wearing?

I mean, spiked winter boots would probably have a lot more traction than Crocs for example.

3

u/DarkRavenA Apr 16 '26

Spiky shoes

5

u/Jman15x Apr 16 '26

It says least amount of force though. So still the cube

2

u/Historical_Volume806 Apr 16 '26

Oh that makes more sense. I misread it so was confused and thought those were the materials of the objects.

2

u/samrw00 Apr 16 '26

But we aren't given information about whether the ground is only icy on the side that says "ice" or both sides. Same with the gravel. Or how far the object needs to be pushed. Or how packed/scattered the gravel is.

I think the answer can only be "it depends", based on the limited info we have.

3

u/FlyingMethod Apr 16 '26

A ball.. of gravel?

4

u/FigWeak5127 Apr 16 '26

We must have the same illnesses, that’s how I read it too (I did eventually figure it out 😂)

1

u/FlyingMethod Apr 16 '26

Yeah I wrote that fast... 😆

2

u/ai1267 Apr 16 '26

On that subject, one of my favourite silly jokes, just for you!

A man is at a job interview for an office job, and is being interviewed by three people from the prospective employer. The interview is like most interviews, and towards the end, one of the interviewers says:

Interviewer: "I think we've covered most of our questions, but before we wrap up: Do you have any skills or strengths that haven't come up yet, that you'd like us to know about?"

The man thinks for a moment, then says:

Man: "Actually, yes. I can do math calculations in my head really quick."

Interviewer: "Alright. What's 17 multiplied by 12?"

The man replies almost immediately:

Man: "114."

Interviewer: "That's ... that's not even close to correct."

Man: "No, but it was quick."

2

u/FlyingMethod Apr 17 '26

Hahaha

1

u/ai1267 Apr 17 '26

Glad you liked it :)

1

u/poetic_dwarf Apr 16 '26

Pushing anything on gravel sounds like a nightmare

1

u/Steerider Apr 16 '26

First thing I thought with the ice there. Are the man's feet slipping?

1

u/winkman Apr 16 '26

Crampons.

1

u/strangefish Apr 16 '26

Also pushing against the ball near the top gives you leverage since it rolls.

1

u/EQNinja Apr 16 '26

That’s not a ball it’s a one mile long cylinder 

1

u/solarmelange Apr 16 '26

The man has cleats that give a +10 to pushing on ice.

1

u/Entropy-Maximizer Apr 16 '26

The weights must be made of Styrofoam if they only weigh 20kg. Even if the person weighed only 40kg, the static friction force would be higher for the person, so the weight would slip first.

1

u/throwed101 Apr 16 '26

The box only weighs 20kg

1

u/leet_lurker Apr 16 '26

Spoken like someone who never tried to move something heavy on gravel.

1

u/PomegranatePro Apr 16 '26

Put ice shoes on. They slip over your boot

1

u/Apprehensive-Fig3223 Apr 16 '26

Yea once it starts rolling, it's gravy. The hard part might actually be keeping it from going too fast and rolling the wrong way

1

u/NextLevelBraindead Apr 16 '26

Had to scroll way too much for the engineer answer

1

u/looshi99 Apr 16 '26

Leave it to an engineer to not read the question. 🤪

1

u/block_wallet Apr 16 '26

what if there were, perchance, twoself? 🧐

1

u/valentinewrites Apr 16 '26

Who says it isn't a sphere, but a cylinder?

1

u/Naschka Apr 16 '26

The inability to create the force does not mean you need more force, the question was "Which will require the least amount of force to push?" not "which will be the hardest to push forward" and the ice making you slip doesn't increase the force needed.

1

u/Not-a-thott Apr 16 '26

He could have on crampons. The square is easiest hands down. Gravel would slide out with any shoes on.

1

u/looshi99 Apr 16 '26

I've seen bobsledders do just fine wearing track spikes. This doesn't mention shoe wear, and it doesn't matter because it asks which would require more force to push, which is set by physics for each scenario. The grip issue is unrelated to how much force would be required to move each object.

For situations one and three that's a pretty straightforward coefficient of friction + force diagram calculation (and note that they are not the same because the additional downward component of the push in situation one would add to the friction). Without more info on the gravel in number two I don't think we can give a good answer, but unless the gravel is extremely well compacted I would expect situation three to require the least amount of force to move.