Pb of elementary mechanics on the springs

[Christophe]

Uh 5000 N not 500 N ...

Yes indeed, but since it is a very short time and we have an energy to dissipate by only 25 joules, it does not matter much.

Bin I would not like to take these 25 Joules on the head ... actually in pure energy it may seem little (it was my feeling too ...) but once we convert that into mechanical force ... bin it's not nothing ...

No need for a dynamometer, we can measure these 2 forces with a balance, if instead of the weight of 5 kg we put a container that we fill, with water or sand, tensioned cable.
To measure the frictional force, it will be necessary to help lift the weight of 10 kg for each test.

Ok i see but this is not Greli's initial experience