Building a gravitational potential energy powered cart for a physics class.
Any advice on maximizing the distance to 9 meters or above? It would have been easy if I were aloud to use elastics, but I am not.
It also must be under one kilo, but that's manageable.
I'm planning on building one similar to the one in the attached pic.
>>910218
Drop it off a 10m platform.
Flywheel. 10M of string. Reducing transmission to wheels.
>>910219
The weight? should have said this before, but the all parts need to be attached to the vehicle, and a 10m platform is too tall to be added to that.
>>910219
It's possible to get those little plastic flywheels at arts and crafts stores right? Or am I just crazy.
>>910218
mgh=0.5mv^2, so you need to maximise the height of the weight
>>910220
This nigga knows what's up.
Pulleys, gears and wheel size.
read this.
>>910218
ball bearings for the wheels, obviously. use giant wheels and tiny diameter spindle to maximize that.
possibly a ratchet for said spindle? you want to allow momentum to keep the car moving when the weight bottoms out, but want to keep the force transfer ideal until that, so making the string exactly that length wont work well because the last few inches of drop it would be slipping too much.
>>910277
I wold think you would want smaller wheels, lower moment of inertia means they will roll easier, also reduces the ratio between the mass determining potential energy and the mass determining kinetic energy, though smaller wheels will have less momentum, and go faster, increasing drag I guess
>>910298
Big wheel will go further because gears.
Small wheel you would have to add gearing and introduce more friction loses.
That's my theory anywise
>>910298
Taking the surface into consideration. If it is not predominantly smooth, larger diameter wheels will have an advantage.
Though right now OP's concern is getting passed 9 meters. Not the speed, energy efficiency or smoothness.
So after he develops his 9m vehicle then he can refine and adjust.
>>910220
This.
Use a small drive axle and put a flywheel on the drive axle, then gear up to increase wheel speed and use large wheels.
Try to come up with a way for the weight's string to detach from the drive axle, like a gyroscope.
>>910218
has the term "cart" been explicitly defined in physical terms, or merely implied as in conventional/traditional conceptualization?
>>910218
Get a 20x21 magnet one up other down, single central wheel on cart, drop marble from 2mtrs onto single wheel, Profit?
Use a magnet to make it fall faster.
![surprise27n-11-web[1].jpg](https://i.imgur.com/FoVWUeh.jpg "surprise27n-11-web[1].jpg")
>STEM field
>asking advice from a forum that regularly brags about what half-eaten food they dug out of dumpsters
Our future. We're doomed.
>>910395
Smart people go to college, so they're smart.
We should have the government pay for dumb people to go to college so they can be smart too!
We should make Asians play more basketball so they can be taller with bigger dicks too.
Op, what are you doing in school. You took a seat from someone who might actually have done something with his STEM degree
>>910218
Are you gonna chromakey some evil forest in the background or something?
First and foremost you need to minimize all losses, rolling losses, bearing losses, and conversion losses.
So make your wheels really round and rigid. Run on a hard smooth surface if you can. Use really good bearings. Magnetically levitated bearings are the best.
Don't 'move' the weight. Use a stationary launcher to shoot a lightweight vehicle like a ball.
Or hook a pulley up to the ceiling and drop the weight from there, use the weight to pull cable on a spool on your vehicle sorta like the below or pull thread off a spool to get it to move
http://durealeyes.com/cablecar.html
Larger height = more stored energy.
Look up videos for optimizing pinewood derby racers.
I recommend dry lubricated ball bearings for wheels. Careful selection is required to minimize frictional losses, and sticky grease in a poorly-chosen bearing will eat up all your energy.
Wheel selection depends heavily on the roughness and elasticity of your surface.
http://www.mhi.org/media/members/14220/130101690137732025.pdf
Probably obvious, but make the vehicle frame and wheels as light as possible to maximize the weight you can have in the weight itself
>>910533
So OP needs to make it out of metallic microlattice for the vehicle and the weight out of osmium?
>>910586
>osmium
Tungsten is almost as good and doesn't cost more per gram than gold.
>>910385
Magnetic weight+platform is probably the only viable cheat for additional distance here.
The extra force could allow you to introduce high ratio gears.
If you really want to push the rules.. helium airship.
Nigga, you gon need bigger wheels and a higher drop point to reach 9 m
Mr Boyarsky's class?
>>910586
No, the weight just needs to be heavy enough to trivialize the mass of the vehicle itself.
Use a ratchet so it continues after out of string
>>910218
A block and tackle set will allow you to multiply the rope distance. It'll be easier to make than gears.
No elastics means no rubber bands. It doesn't meany you can't store a bunch of potential energy in a flexed structural element. If you leverage that energy source to bring you up to speed then you can use a weight/pulley arrangement to maintain your speed for as long as possible.
Wheel slip is your enemy.
>>910298
>>910314
You are both not thinking physics. A higher moment of inertia is good for this application. You are not working off of a set input of force, there is a constant force until you reach a position where the weight stops pushing.
so a machine with a low moment of inertia will hit the point after, say, 5 seconds will have received less energy but achieved a higher speed, whereas a machine with a very high moment of inertia will have taken 8 seconds, be moving slower but have a higher momentum/stored kinetic energy.
So the second machine will go farther as long as frictional losses aren't too large. if frictional losses are too large, the faster speed will be more important to cover distance before it runs down.
>>912945
It kinda does, because anything that flexes and unflexes back is "elastic".
>not a mousetrap car
either your teacher hates fun or mouse traps were deemed to dangerous for this generation of autists.
>>913089
But the weight _itself_ provides that high moment of inertia in addition to storing the actual energy used to get the thing moving.
Assuming identical total weight (which is a concern for OP's 1kg limit), the vehicle with proportionately more mass in the weight should go further.
A pendulum!
>>913181
My better half is a primary school teacher, she's getting more kids every year who don't know their own name, can't use a toilet and communicate via yelps.
The future is fucked.
>>913211
True, but that wasn't the issue. Assuming the mass of the weight stays the same, wheels that are larger but weigh the same (eg wooden wheel vs bicycle style wheel) will have a higher rotational moment of inertia because that mass is distributed more towards the edges.
I'm just saying the argument that a higher inertia will keep it from going as far is false, because slower to speed up means more time for the force of gravity on the weight to start it moving.
>>913211
this isn't necessarily true, btw, it would also have to be substantially similar. I would rather have a smaller weight drop farther than a bigger weight attempt to kick it off.
