Quarter Mile times... from a plane?

# Thread: Quarter Mile times... from a plane?

1. ## Quarter Mile times... from a plane?

Someone want to help me out with the math here?

I'd like to know what a 1/4 mile time would be for a bike (or any object i guess) dropped from a plane.
I know the whole 32 feet per second squared and d=1/2at(squared) but I'm too lazy to attempt to factor in air resistance and 1/4mile math. Anyone give a little help?

It would be interesting to know if a bike dropped from a plane has a faster time then say a 1000cc on the ground. I honestly can't guess.

2. ok, can anyone just guess which would be faster? A bike doing a vertical drop 1/4mile or one on the drag strip?

3. 1/4 mile drop I imagine.

4. If a bike was travelling 300km/hr that is 273 feet per second. So i'd guess its not even close.

5. ignoring air friction, 400m=0.5*9.8t^2 ===> t=9s which is faster than how fast they can travel on land.

if you want to take into account air friction, you have to use some fluid dynamics. However, there's no way to judge what the velocity profile of a motorcycle streamline is which makes it hard to say. Also, there's a good chance that the motorcycle will be at terminal velocity after 9 seconds. Ignoring friction, the bike will be approximately 90 m/s == 324 km/h.

So, looking at terminal velocity...http://en.wikipedia.org/wiki/Terminal_velocity
shows that terminal velocity on a person is about 54m/s. On a bike, I'd imagine it'd be smaller. Let's assume 45m/s. Therefore, the bike would reach terminal velocity at 45m/s. So let's neglect air friction for the first 5 seconds and integrate the velocity over time to get distance.

400 = 0.5*9.8*5^2+45*t ===> t= 6.1667
total time = 5 + 6.1667 = 11.1667

Taking figures from http://www.motorcycle-usa.com/Articl...ID=4514&Page=2
which has the cbr600RR 1/4 mile time clocked at 10.6, we can compare the two times.

IF we were to consider air friction for the first 5 seconds, the time for the free fall would be even higher.

Also, to make sure, using the same math for terminal velocity = 54m/s, we still yield 10.9 which is still larger than 10.6

in conclusion, on the ground = faster

6. Originally Posted by Ratzilla
ignoring air friction, 400m=0.5*9.8t^2 ===> t=9s which is faster than how fast they can travel on land.

if you want to take into account air friction, you have to use some fluid dynamics. However, there's no way to judge what the velocity profile of a motorcycle streamline is which makes it hard to say. Also, there's a good chance that the motorcycle will be at terminal velocity after 9 seconds. Ignoring friction, the bike will be approximately 90 m/s == 324 km/h.

So, looking at terminal velocity...http://en.wikipedia.org/wiki/Terminal_velocity
shows that terminal velocity on a person is about 54m/s. On a bike, I'd imagine it'd be smaller. Let's assume 45m/s. Therefore, the bike would reach terminal velocity at 45m/s. So let's neglect air friction for the first 5 seconds and integrate the velocity over time to get distance.

400 = 0.5*9.8*5^2+45*t ===> t= 6.1667
total time = 5 + 6.1667 = 11.1667

Taking figures from http://www.motorcycle-usa.com/Articl...ID=4514&Page=2
which has the cbr600RR 1/4 mile time clocked at 10.6, we can compare the two times.

IF we were to consider air friction for the first 5 seconds, the time for the free fall would be even higher.

Also, to make sure, using the same math for terminal velocity = 54m/s, we still yield 10.9 which is still larger than 10.6

in conclusion, on the ground = faster
You lost me at "ignoring air friction". I did undermastand your last line though.

7. a bologna sandwich dropped would beat the bike. its almost like whats heavier, a lb of feathers or a lb of lead?

8. wouldn't the sandwich tie the bike?

9. Originally Posted by Hogie
wouldn't the sandwich tie the bike?
if the sandwich was tied to the bike on the track?

10. ..........

11. Originally Posted by bradnailer
if the sandwich was tied to the bike on the track?
I thought they were falling?

12. hahahaahahah it sure is.

13. Originally Posted by Ratzilla
So, looking at terminal velocity...http://en.wikipedia.org/wiki/Terminal_velocity
I just gotta segway here, check that wikipedia article for the reference to the Air Force captain: So he jumped out of a balloon at 102,800 feet altitude? And hit 614 mph during freefall? That's crazy!!!

14. Originally Posted by Squint
I just gotta segway here, check that wikipedia article for the reference to the Air Force captain: So he jumped out of a balloon at 102,800 feet altitude? And hit 614 mph during freefall? That's crazy!!!
At that altitude the air is all but non existant so the terminal velocity would be very high. Apparently 614 mph.

A little sidenote. At roughly 18,000 feet you've got half the air below you and half of it above you. Each additional 18,000 feet divides the last value in half again. So at 36,000 you've got 3/4's of the air below you and 1/4 of it above you. So those jet airliners are holding you up while only flying through air that is 1/4 or less the density we see at sea level.

On the moon a pound of feathers and a pound of lead both fall at the same speed.

15. Originally Posted by TeeTee
At that altitude the air is all but non existant so the terminal velocity would be very high. Apparently 614 mph.

A little sidenote. At roughly 18,000 feet you've got half the air below you and half of it above you. Each additional 18,000 feet divides the last value in half again. So at 36,000 you've got 3/4's of the air below you and 1/4 of it above you. So those jet airliners are holding you up while only flying through air that is 1/4 or less the density we see at sea level.

On the moon a pound of feathers and a pound of lead both fall at the same speed.
yes. In a vacuum all objects fall at the same rate.

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