zing
Platinum Member
Four women in high heels pulled a locomotive back in ~1930 for a Timken bearing ad.
Pulling Steam Locomotives by Hand | PenneyVanderbilt
Yeah, but could they stop it going down hill? Better dig in those heels! :thumbsup:
Four women in high heels pulled a locomotive back in ~1930 for a Timken bearing ad.
Pulling Steam Locomotives by Hand | PenneyVanderbilt
Yeah, 1k tons is a bunch of weight BUT.....how did people from long ago move stones that weigh 1600 tons?
The Largest Stones Ever Quarried | Select Stone
....these questions and answers are making my head explode. :banghead:
It's like asking: "How many oranges do I need to make an apple pie?"
Here goes:
1000 tons = 907,185 kg.
On earth, Gravity (g) accelerates objects at 9.81m/s^2, the rock with a mass (m) of 907,185 kg exerts a downward force (F=mg) on the trailer of (F=907,185kg x 9.81m/s^2 = 8,900,000 Newtons (or 8.9 mega-Newtons)
If there could be zero friction, in the trailer bearings, tire rolling resistance, air resistance, and on level ground, just the slightest of slight force (F) could move it horizontally. Specifically, this force would accelerate it at a rate that can be calculated. Force = mass x acceleration (F=m x a); or acceleration a = F/m. This acceleration would occur for as long as you applied that force. Given an infinite amount of time any force would accelerate it to light speed (if there is no friction or hills).
In "reality" (I know, a 1000 ton rock!), the "trailer"(!) has friction that needs to be overcome.
Here's where the problem gets tricky, as often this friction, and the force required to overcome it, is not a constant; or even linear. (Example: How much force is required to overcome wind resistance on a 10 ton truck? It depends not that the truck is 10 tons, but how fast it's going and it's shape (surface area, etc..))
....but for the sake of simplicity, let's say this friction is a constant 1% of the weight. (i.e. the coefficient of friction is .01).
(Example: I regularly push my 3000 lb sedan out of my flat garage with one hand; once rolling applying about 30 lbs of force easily keeps it at speed. So, coefficient of friction is about 1%. Follow?)
That is, while gravity is causing the rock to exert a downward force of 8.9 megaNewtons downward, we'll say it takes a Force (8.9 megaNewtons x .01 =) 89 kiloNewtons to overcome the friction and maintain a constant speed (neither accelerating or decelerating) once moving.
So any force over 89 kiloNewtons will start the trailer accelerating.
Applying 89 kiloNewtons on a 300km trip requires (89kN x 300 km = 26.7 x10^9 Newton-meters (or Joules). That's 26,700 kJ (kilo-joules) of ENERGY required for the trip.
Now HOW FAST DO YOU WANT TO MAKE THE TRIP? THAT determines the POWER that's required.
1 Watt = 1 Joule/sec.
Want to do it in 10 hours (36,000 seconds)?
Then it takes: 26,700 kJ/36,000s = 741.7 kiloWatts.
1 horsepower = 746 Watts, so that's: 1000 hp, just to overcome the friction at speed. ....on flatground.
You also need horsepower (actually: Force / torque) to accelerate it up to your travel speed of 30 km/h (for a 10 hour trip).
Let's say you only want to take 10 minutes to accelerate. (That's 600 seconds to get up to a speed 8.33 meters/sec (30 km/h). That's an acceleration rate of .0139m/sec^2
To accelerate the 907,185 kg rock at this rate requires a force of (F=m x a)= 12.6 kiloJoules of torque (9293 foot-pounds)(but only about 21hp!), on top of the 1000 hp it takes to maintain speed. (Yeah, I'm mixing units.)
You then need to brake that 1000 tons at the destination! Finding the equipment that does this (tractor and trailer) may be difficult. And if there's any hill or inclines....you're going to need a bigger tractor!
Maybe in theory. Even 1000 hp is only one hp per ton for the load itself. The trucks and trailer is probably another 1000 tons. Imagine trying to move a car with 1 hp. I guess it’s do able with enough gears but it would be turtle slow on flat ground and probably measured in inches per hour up hill. Using the fairly generous sounding rating of 300 hp my dump truck has 18 hp per ton loaded and it’s 30 or so mph up hills. A load like that will never hit 30 mph on flat ground but still only 1/2 hp or so per ton isn’t even close to enough.