the forces involved are higher than you might think.
its a simple matter of A-level maths and the equations of motion (brings back memories this)
Force = mass x acceleration
we know that the mass of say a 650 litre system is about probably about 680kg, but what is the acceleration? (or decceleration in this case)
the equation of motion to use in this case will be v=u+at where v=final speed, u= initial speed t=time and a=acceleration.
v(final speed) will be zero
u(initial speed) will be 30mph which is 13.41metres per second in SI units
t is the time. I think its safe to say that if you had a crash into a solid object you'd come to a stop within quarter of a second, so i'm assuming this is 0.25
so, rearranging that equation to find the accelleration gives us:
(v-u)/t = a
(0-13.41)/.25 = a
so the acceleration a=-53.64 m/s/s
(its a negative number cos its deceleration, but the magnitude of the force is still the same)
so the force exerted by a 680kg load travelling at 30mph, and stopping in quater of a second is:
Force = mass x acceleration
Force = 680 x -53.64
Force = -36,475.2 kg
or 36.4752 tonnes, and that is only at 30mph
so your restraints need to be able to hold 36 tonnes.
My old maths teacher would be proud!
