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Physics problem
#7
The energy needed to compress the spring is indeed [Image: gif.latex?%5Cbg_white%20%5Cfrac%7B1%7D%7...l_0%7D%5E2]
but 10 cm = 0.1 m ;) (

You should proceed step by step. First, what is the total energy E when the mass is dropped ? Its not moving at this very moment so K = 0. But it has some gravitational energy. If we choose the reference so that the gravitational energy down the slope is 0, then [Image: gif.latex?%5Cbg_white%20E%20%3D%20E_0%20%3D%20mgh].

When the mass gets down the slope, the total energy is still the same as before ([Image: gif.latex?%5Cbg_white%20E%20%3D%20E_0]) because there was supposedly no friction. The only difference is that the energy was entirely transformed under its kinetic form (E = K), because the mass reached a position where its potential energy is 0.

The energy required to move along the path is obtained from the work of the friction force which is now taken into account. This force is constant during the motion. Thus, [Image: gif.latex?%5Cbg_white%20%5CDelta%20E%20%...CDelta%20x] so that at the end of the path
[Image: gif.latex?%5Cbg_white%20K%20%3D%20E%20%3...CDelta%20x]
(F can be calculated from the weight of the object and the friction coefficient)

Now, the kinetic energy has to be greater than the elastic energy required (which you calculated already).
Thanks given by:


Messages In This Thread
Physics problem - by Andrez - 25 Sep 14, 09:35PM
RE: Physics problem - by DeafieGamer - 25 Sep 14, 11:17PM
RE: Physics problem - by Orynge - 26 Sep 14, 01:09AM
RE: Physics problem - by Luc@s - 26 Sep 14, 12:28PM
RE: Physics problem - by Mousikos - 26 Sep 14, 01:40PM
RE: Physics problem - by Andrez - 26 Sep 14, 04:50PM
RE: Physics problem - by Luc@s - 26 Sep 14, 05:45PM
RE: Physics problem - by Andrez - 26 Sep 14, 05:52PM
RE: Physics problem - by Luc@s - 26 Sep 14, 06:28PM
RE: Physics problem - by Marti - 26 Sep 14, 07:16PM
RE: Physics problem - by Andrez - 26 Sep 14, 08:00PM
RE: Physics problem - by Mousikos - 26 Sep 14, 08:20PM
RE: Physics problem - by Luc@s - 26 Sep 14, 08:36PM


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