dj park

[jerseydirt]

i really dont feel like going all the way to highbridge. i wanna smooth out upper dominion a little so i can ride it on my hardtail. it was so bumpy last time. Maybe there should be a dirt jumps park in that space by phantom drop so when your done dirt jumping you can do the drop.

[Timekiller]

heh.. did you see uppers on diabloween? that was crazy

[downhillbkr247]

upper was a S#1THOLE...or should i say MUDhole lol during diabloween...for once i wished i had tear-offs!

[NJMX835]

The good news is Diablo will be installing tampon & pad dispensers at the top of every trail this year.

No more leakage! :thumb:

[runnin12s]

are there gonna be bathrooms to go with those feminine products?:clapping:

[Timekiller]

The good news is Diablo will be installing tampon & pad dispensers at the top of every trail this year.

No more leakage! :thumb:

dude, this is crymonkey.com.... er i mean ride.

[demo 9]

how many seconds will u spend in the air in a season at the diablo jump park...lol

[Timekiller]

how many seconds will u spend in the air in a season at the diablo jump park...lol

haha.... ill bite

Lets say average of 3 seconds / drop
15 drops in a day
every day of the season (105)

That would be 45sec./day
4,725sec/season or 78.75min/season
or just about 1-1/2 hours of flight
:imstupid::banana::ban:

[jcook90]

3 seconds a drop is very very off. Clearly your understanding of gravity is off, but all of your other math/physics is right. Gravity is 32 ft/second/second, so in 1 second you fall 16 feet, resulting in typical airtime off the normal drop (say 8 feet) to be roughly .75ish seconds (speed increases the more you drop so you cover more in the last increment of time). Jumps can be interpreted slightly different, you get double the time for the same height achieved as drops. Say you get 16 feet up on a domination drop, then your airtime would be 2 seconds because of the above mentioned constants. Close though, the other stuff about rotation on wheels, moments of intertia, centripietal force, etc was all pretty cool.

Oh, and yes, pvssys

[The303Kid]

there not that much room above deck for jumps but it would still be sick

[demo 9]

eye kan skip werds too

[Timekiller]

3 seconds a drop is very very off. Clearly your understanding of gravity is off, but all of your other math/physics is right. Gravity is 32 ft/second/second, so in 1 second you fall 16 feet, resulting in typical airtime off the normal drop (say 8 feet) to be roughly .75ish seconds (speed increases the more you drop so you cover more in the last increment of time). Jumps can be interpreted slightly different, you get double the time for the same height achieved as drops. Say you get 16 feet up on a domination drop, then your airtime would be 2 seconds because of the above mentioned constants. Close though, the other stuff about rotation on wheels, moments of intertia, centripietal force, etc was all pretty cool.

Oh, and yes, pvssys

Thank you for the correction. I just pulled the 3 seconds out of my @$$. I was being lazy as usual and didn't look it up. I also didn't realize we were talking about jumps instead of drops.

Drops:
Lets say average of .75 seconds / drop
15 drops in a day
every day of the season (105)

That would be 11.25sec./day
1,181.25sec/season or 19.67min/season
or just about 1/2 hour of flight

Jumps:
Lets say average of 2 seconds / jump
30 jumps in a day
every day of the season (105)

That would be 60sec./day
6,300sec/season or 105min/season
or just about 1-3/4 hours of flight

[jcook90]

Bueno.

How about now total volume of brake fluid moved per year, saying 2mL of fluid are moved in the average braking (that's just one way, 4mL all together). Say you brake uhh 15(?) times a run.

[Timekiller]

Bueno.

How about now total volume of brake fluid moved per year, saying 2mL of fluid are moved in the average braking (that's just one way, 4mL all together). Say you brake uhh 15(?) times a run.

30ml/run (1 way) 60ml/run (2 ways)
20 runs / day...
600ml/day(1 way) 1200ml/day (2 ways)

about 20 oz/day one way... 40oz 2 ways.

So you move about this much fluid in one day:

http://www.mybeerpix.com/images/2007/06/old-800.jpg

and if you rode the whole season (105 days) you would move 105 old E's in the season.

[jcook90]

I'm starting to run out of ideas here...

Heres one:
The rotational kinetic energy of a 1.3kg .66m diameter wheel with a 20t chainring and a 38t front chainring rotating at 2(pi) rad/second (the cranks, that is)

Also, the perpendicular force required on a 175mm front crank with 38t chainring attached to the same rear wheel to get it to accelerate at 3 rad/sec/sec.

GO!

Also, how bored are you? And i'm guessing you paid attention in physics class if you can solve those two

[Timekiller]

I'm starting to run out of ideas here...

Heres one:
The rotational kinetic energy of a 1.3kg .66m diameter wheel with a 20t chainring and a 38t front chainring rotating at 2(pi) rad/second (the cranks, that is)

Hmm... so the crank is rotating at 2(pi) rad/second and with a 1:1.9 ratio the wheel is spinning at (1.9*2(pi)rad/sec)
155.12"/sec or 8.913MPH
Angular velocity is 684º/sec
Moment of inertia is .429kg*M

ERotational= 1/2Iw(2)
Erot= 1/2(.429)(467856)
Erot= 2.007

Therefore the RKE should be 1.00355112kg*m
or
9.8414746 joules

Also, the perpendicular force required on a 175mm front crank with 38t chainring attached to the same rear wheel to get it to accelerate at 3 rad/sec/sec.

well the force required to spin the static wheel at that acceleration is:
1.287kg-m or 9.3088888ft-lbs.
so
the static force required at the crank is:
2.4453kg-m or 17.687ft-lbs.
which means
if the front chainring has a radius of 79mm the leverage ratio is 2.215 (mechanical adv.)
then
you would need to apply 1.1046571kg-m or 7.99 ft/lbs. to the pedals. Unfortunately I have to leave work right now so Im not going to figure out the force in the arc (perp. force) Ill do it tomorrow.


Also, how bored are you? And i'm guessing you paid attention in physics class if you can solve those two

...never took physics.. :poster_oops:

[Timekiller]

I got another to figure out tomorrow. (http://www.ridemonkey.com/forums/showthread.php?p=2795733#post2795733)

[jerseydirt]

3 seconds a drop is very very off. Clearly your understanding of gravity is off, but all of your other math/physics is right. Gravity is 32 ft/second/second, so in 1 second you fall 16 feet, resulting in typical airtime off the normal drop (say 8 feet) to be roughly .75ish seconds (speed increases the more you drop so you cover more in the last increment of time). Jumps can be interpreted slightly different, you get double the time for the same height achieved as drops. Say you get 16 feet up on a domination drop, then your airtime would be 2 seconds because of the above mentioned constants. Close though, the other stuff about rotation on wheels, moments of intertia, centripietal force, etc was all pretty cool.

Oh, and yes, pvssys

gravity has a force of 9.8

[Huck Banzai]

Ok.

How much wood could a...could an educated beaver chuck if properly instructed by a qualified woodchuck? (Given up-to-date Union membership and medical clearance.)

[rollertoaster]

how much wood could a woodchuck chuck, if a woodchuck could Chuck Norris?

[demo 9]

none, chuck norris would roundhouse kick it

[JerZ_r1der]

After reading this post... it reminded me of everything I hated in Physics class. :]

[jcook90]

gravity has a force of 9.8

Even though I'm done with school, 9.8 m/s^2 which equals 32 feet/s^2. And 9.8 is just the acceleration due to it, the force of gravity is different.

[ICU812]

fourth day, five day marathon, were moving like a parallelogram.

[FBMX123]

lets talk about olde enlish again! I actuall prefer the Colt 45, but when i'm feeling particularly frisky, i like to roll with the good ol' 211. And if i just got done rocking out to Ice Cube and Dre, I grab the St. Ides...**** "gets yo jimmy thicka, gets ya girl in the mood quicka." word

[chatua]

3 seconds a drop is very very off. Clearly your understanding of gravity is off, but all of your other math/physics is right. Gravity is 32 ft/second/second, so in 1 second you fall 16 feet, resulting in typical airtime off the normal drop (say 8 feet) to be roughly .75ish seconds (speed increases the more you drop so you cover more in the last increment of time). Jumps can be interpreted slightly different, you get double the time for the same height achieved as drops. Say you get 16 feet up on a domination drop, then your airtime would be 2 seconds because of the above mentioned constants. Close though, the other stuff about rotation on wheels, moments of intertia, centripietal force, etc was all pretty cool.

Oh, and yes, pvssys

Come again? :brow:
32ft/sec/sec is the acceleration of gravity. The very instant you leave a drop, your rate of decent is 0ft/sec, and the more time you spend airborne, the faster you fall.

As you should know, the formula for distance traveled knowing only initial velocity, acceleration, and time is D=V0*t+at^2. Since initial velocity is 0 for a drop, you get D=at^2. This gives the distance fallen from an initial velocity of 0 in 1 second as 32ft...duhhh, not 16ft.

Using the above equation, we can calculate normal airtime for a drop like Phantom. Let's use 8ft like you did:
8ft=(32ft/sec^2)t^2
t^2=(1/4)sec^2
t=0.5 second

Now, I really don't feel like calculating how many seconds Dom's Denial, Road to Nowhere, Anthem, the jumps, etc. would take. But if anyone wants to try, use the formula I used, multiply that by the number of times you hit the drop per day, add it to the other drops you hit, times it by number of times you visit a season, etc. For jumps, estimate the height you get off the jump and treat it like it was a drop. Just multiply it by 2 cuz you spend the same amount of time going up as you do going down. Unless of course...it's a step up/step down like the Salvation kicker, thats a different story. :crazy:

[DEMOmy8]

anyone here wanna be my math tutor? :P

[DownCycles_Stef]

3 seconds a drop is very very off. Clearly your understanding of gravity is off, but all of your other math/physics is right. Gravity is 32 ft/second/second, so in 1 second you fall 16 feet, resulting in typical airtime off the normal drop (say 8 feet) to be roughly .75ish seconds (speed increases the more you drop so you cover more in the last increment of time). Jumps can be interpreted slightly different, you get double the time for the same height achieved as drops. Say you get 16 feet up on a domination drop, then your airtime would be 2 seconds because of the above mentioned constants. Close though, the other stuff about rotation on wheels, moments of intertia, centripietal force, etc was all pretty cool.

Oh, and yes, pvssys

Wow, I really don't want to bite into this one, but this is what I get for majoring in physics...gravity is -32ft/(s^2), it's a measure of acceleration. Here's the only other equation you need... Distance (ft) = ( Velocity (ft/s) * Time (s) ) + (Acceleration (in this case G, which is -32ft/s^s) * Time^2 (s^2) ).

Have fun figuring this nonsense out and remember your initial vertical speed is typically 0 ft/s not how fast you are actually moving off the jump, in fact on kickers like Salvation your initial vertical speed is probably more than 0. And in general a negative speed or acceleration or distance means the object in question is moving towards the origin of gravity (i.e. the ground).

Oh, yeah, and I can ride too, haha.

[tmoney727t]

you guys are nerds.

[jerseydirt]

funny how this is a dj park thread

[downhillbkr247]

i love this thread! its an educational fight!

[jerseydirt]

yeah tis why it hasnt been deleted

[fortenndu]

Jcook90 got F-d in the ass.

[downhillbkr247]

i believe that the politically correct term is: OH SH13TTTTTT!!!! Jcook90 JUST GOT F'D IN THE A!!!!!!!!!!!

[mntbiker2]

j cook likes it in the a!!