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jerseydirt

Turbo Monkey
May 6, 2007
1,936
0
dirty jerz
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

Monkey
Oct 9, 2006
697
0
NJ
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

Turbo Monkey
Mar 3, 2006
1,211
0
Connecticut
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
 

Timekiller

Monkey
Oct 9, 2006
697
0
NJ
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

Turbo Monkey
Mar 3, 2006
1,211
0
Connecticut
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

Monkey
Oct 9, 2006
697
0
NJ
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:



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

jcook90

Turbo Monkey
Mar 3, 2006
1,211
0
Connecticut
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

Monkey
Oct 9, 2006
697
0
NJ
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:
 

jerseydirt

Turbo Monkey
May 6, 2007
1,936
0
dirty jerz
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

Turbo Monkey
May 8, 2005
2,526
21
Transitory
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.)
 

FBMX123

Chimp
Aug 2, 2007
16
0
Connecticut
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

Chimp
Jul 3, 2007
22
0
201
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:
 
Apr 28, 2006
235
0
North White Plains, NY
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.