Why can crashes be considered two separate collisions?

Amass-spring-viscous damper system of mass 3 kg has a frequency of 100 rad/s and is critically damped. its initial conditions are x(0)-3 mm and (0)-2.3 m/s. does the system overshoot its equilibrium position? prove your answer

Asolid steel sphere (k=63.9 w m-1 k-1 , ? =7832 kg m-3 , c=0.523 kj kg-1 k-1 ), 100 mm in diameter is initially at a uniform temperature of 500o c and is suddenly quenched in a large oil bath for which t? = 100o c and h = 3200 w m-2 k-1. estimate the time required for the sphere to cool to 200o c and to 110o c

Aload of 10kn is to be suddenly applied to the free end of a vertical rod of length 500 mm, the upper end being rigidly fixed. 190 mechanical science what should the diameter of the rod be if the maximum stress in the rod is not to exceed 100 mpa? the tensile modulus of the rod is 205 gpa.