Local lad killed by towball

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Originally Posted by whitakerb

Pack the shovel next time

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Ok.

cheers

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Originally Posted by mark2

I thought the units of power are Watts??? (1 Watt = 1 Joule/second)

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You are correct. It was late, that's my excuse:eek:

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Originally Posted by Mr Whippy

No I am not pulling your leg.
I do understand all about Kinetic and potential energy.

What I didn't understand and still don't is how to interpret the formula.

Your original post had this,

Kinetic Energy (KE)= (1/2)m.v^2 Units are joules (or kg/sec^2)

Force = m.a Units are Newtons (or kg.m/sec^2)


Ok the (KE) means Kinetic Energy.

(1/2)m I assume means half the mass. Why is the 1/2 bracketed?

Now v is velocity and I have guessed that ^2 means squared.

What is the decimal point between m and v

Dave.

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Dave,

The 1/2 was bracketed because I thought it would make it clearer that I was writing a fraction, I could have written 0.5 but it is seldom written as a decimal multiplier. Yes the 1/2 applies to the whole product of mass and velocity squared, so taking 1/2 the mass and multiplying it by the velocity squared will give you the correct result.

a dot in some circles can mean multiplication, I could have left it as 1/2mv^2 or 1/2 x m x v x v but thought that the x would get confused for a variable instead of the multiplier sign.

I should have gone to bed instead of thinking about Newton's Laws of motion.

When I went to school the equation would be written like this

https://www.aulro.com/afvb/

When I was in year 8 at school we were sent home to watch man land on the moon on a black and white TV.

So this is why I couldn't understand the modern version, especially the dot between m&v.

Dave.

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Originally Posted by Mr Whippy

When I went to school the equation would be written like this

http://img190.imageshack.us/img190/9969/equationr.jpg

When I was in year 8 at school we were sent home to watch man land on the moon on a black and white TV.

So this is why I couldn't understand the modern version, especially the dot between m&v.

Dave.

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Sorry Dave, I can't believe you. The image you've displayed looks like a dry marker on a white-board. If you were going to school when Neil was walking on the moon one day on your B & W TV. Then the equation would have been written on a black-board (which were usually green) in chalk! :p ;)

But I get your drift!

Diana

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Originally Posted by Lotz-A-Landies

Sorry Dave, I can't believe you. The image you've displayed looks like a dry marker on a white-board. If you were going to school when Neil was walking on the moon one day on your B & W TV. Then the equation would have been written on a black-board (which were usually green) in chalk! :p ;)

But I get your drift!

Diana

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Black texta on a piece of paper.

Dave.

In my world we use * for multiplication to avoid confusion with x which, as you say, could be mistaken for a variable.

The . notation took me a couple of secs to work out and I assumed was old school.

I am wanting someone to point out in simple terms the flaw with the walking speed with snatch strap to pull someone out argument. The way I read that, if you vehicle was just a bit bogged then you could self recover with a snatch strap and a pair of shoes with good traction :D

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Originally Posted by DiscoStew

I am wanting someone to point out in simple terms the flaw with the walking speed with snatch strap to pull someone out argument. The way I read that, if you vehicle was just a bit bogged then you could self recover with a snatch strap and a pair of shoes with good traction :D

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Sure could.

If you weighed 2 tonne

The mass is doing the work so you better get down to maccas pronto

Ben

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Originally Posted by Disco_Dan

its a tragic thing to have happened and as has been said before it stresses the use for common sence , rated recovery gear and points , i like to winch rather than snatch unless all that is needed is a gentle pull like a tow , also making sure there is nobody in close proximity to whats going on especially inside the car besides the 2 drivers.. i suppose hindsight is a wonderful thing. but things like this happening are going to quickly destroy whatever privilages we have left as offroad enthusiests im sure many will agree.. Just my 2 cents. Dan.

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i agree with you Dan i paid more money for my warn winch than my recovery points and strap ,so why not use it if you got it ???????'shock loads from snatching are unbeleivable

at least i am getting my moneys worth and have control over the situation

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Originally Posted by whitakerb

Say for example my Rangie is up to its sills in mud and isn't going to go anywhere easily, suggesting as per US Army manual it will need approx 18T of force to remove from the hole

Snatch strap is attached to my Rangie and recovery vehicle with a 3500kg bow shackles.

If the recovery vehicle moves at walking pace and my maths are correct you will apply the following force on your gear.

For the sake of the argument, my Rangie is an immovable object and we are ignoring any other outside forces.

Mass = Recovery vehicle = 2000kg

Velocity = walking pace = 3km/h = 0.833333m/s

F = X KG

X= M*V

= 2000*0.83333 = 1666.66

Force = 1666.66KG

So not too much, but to overload the bow shackles we only need 3500kg of force;

F = 3500

M = 2000

V = F/M

3500/2000

1.75m/s = 6.3KM/H

So again if my maths are correct, you need to be doing 6.3km/h to overload a 3.5 T Bow shackle, however you are not likely to break it due to its safety factor which is IIRC 500% so 17.5T

Not much IMHO

Now say the Reece hitch was fully welded, and rule of thumb is 1 inch of weld will hold 1000kg then:

Reece hitch is 50x50mm = 8 inches of weld = 8000kg breaking strain, were not looking at a great deal of speed to create a lethal object.

If anything, make sure you pack your shovel next time so you can do the walking pace recoverys rather than trying warp speed to 'pop' it out of the bog

So condolences out to the victims family and hopefully it wakes us all up when on the tracks

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very well discribed in the speeds which are required ,i see snaches (LOL) been done where i can not get me and my family out of there quick enough SCARY STUFF:eek: