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l   k l , (7.15)
д д c
and considering a linear relationship between stresses and strains,
we obtain

  k  , (7.16)
д д c
where  – stress that occurs in the material of the rod
c
under static loading of.
The expression for the dynamic coefficient (7.14) can be
written in another form if we use the relationship between the
height h and speed  at the moment of collision. Knowing
v  2gh where h   2 2g we obtain

 2
k  1 1 . (7.17)
д
g l
c
0
0
When the load is applied suddenly (  , h  ), then
k  2, and l  2 l ;   2 .
д д c д c
If cargo falls from a great height 2h    2 g l  1,
l
c c
the expression for the dynamic coefficient can be written more
compactly without sacrificing accuracy:
2h  2
k   . (7.18)
д
l  g l
c c
7.2.3 Transverse impact

Let the beam falls freely from a height h of load P (fig.
7.4 a). Solving the problem is the same as the longitudinal
impact, come to the key equation

2
y  2y y  2hy  .
0
д c д c

b)
82
Figure 7.4