Solutions of Savchenko Problems in Physics

Aliaksandr Melnichenka
October 2023

Statement

$2.1.15.$ The body of mass $m$ is connected by two springs of stiffness $k_1$ and $k_2$ with fixed walls, the springs are not initially deformed. When vibrations occur, the greatest acceleration of the body is $a$. Find the maximum deviation of the body from the equilibrium position and the maximum forces with which the springs act on the walls.

For problem $2.1.15$

Solution

Equivalent system of springs

1. The springs in this problem are connected in parallel, their deformation is the same $$ Δx_1 = Δx_2 = Δx $$ 2. The force acting on the mass from the springs is determined as the sum $$ F = F + F_1 $$ alternatively $$ k \Delta x = k_1 \Delta x + k_2 \Delta x $$ 3. Let us write down the equation of motion of the mass under the action of an equivalent spring with stiffness ko, which will allow us to determine the maximum displacement $$ ma = (k_1 + k_2) \Delta x_{max} $$ $$ \Delta x_{max} = ma/(k_1 + k_2) $$ 4. Maximum values of forces acting on the mass $$ {F_1}_{max} = k_1 \Delta x_{max} $$ $$ {F_2}_{max} = k_2 \Delta x_{max} $$

Answer

$$x_{max} = ma/(k_1 + k_2);$$ $${F_1}_{max} = k_1x_{max}$$ $${F_2}_{max} = k_2x_{max}$$