"Steven Shelikoff" wrote in message
...


I'll define a problem

Can I play too??????

distance from hitch to axle is 10' and the tongue weight is 100lbs.

Okay, that is 10' x 100 lbs = 1000 ft-lbs moment around the axel.


Now increase the length of the tongue to 15' from axle to hitch.

1000 ft-lbs / 15 feet = 66.666 pounds.


center of mass of the extension is 2.5' from the hitch and 12.5' from
the axle. So what percentage of the weight of the extension is
supported by the hitch?

12.5' / 15' x 100 = 83%


Knowing the percentage of the weight of the extension that's supported
by the hitch, how much does the extension have to weigh to exactly
counteract the decrease in weight due to leverage and keep the weight on
the hitch at 100lbs?

33 lbs / .83 = 40.1 lbs.

Bonus question: assume that the original level trailer with the 10' from
axle to hitch weighs 1000lbs and the hitch weight is 100lbs, or 10% of
the trailer weight.

100 lbs x 10 feet = 1000 ft pounds. This means that the center of mass for
the trailer is 1 foot forward of the axels.

You extend the tongue by 5' using an extension that
weighs 10 lbs/ft.

We have added 50 pounds of material that has a center of mass 12.5 from
the axel. The moment about the axels would be 50 lbs x 12.5 ft = 625
ft-lbs. Total moment is now 1625 ft-lbs. The new tongue weight will be
108.3 pounds.

The new trailer weight is 1050 pounds.

1625 ft-lbs / 1050 pounds = 1.5 feet, thus the new center of mass is 1.5
feet in front of the axel, or 13.5 feet from the hitch.

How far and in what direction do you have to move the
axle to keep the hitch weight 10% of the new trailer weight?

The desired of tongue weight of 10% would be 105 pounds.
To get this, the distance from the hitch to the center of mass (13.5 feet)
needs to be 10 times greater than the distance from the center of mass to
the axel. Thus, the distance from the center of mass to the axel is 13.5/10
= 1.35 feet.

Answer: The axel will have to move FORWARD 0.15 feet



Did I get it right? Huh? Huh? Huh?
Do I get a star on my paper?????


Rod McInnis