Question

Why is mechanical energy = stress multiplied by strain?

Answer 1

We know that when a material behaves elastically, the work done on straining it is stored as energy in it. We call this (elastic) strain energy. We can derive the strain energy density (ρe) in a material by calculating the area under its stress - strain graph. The definition of the density of energy is analogous to the definition of the density of mass. It is the energy stored per unit volume (how many joules are stored in 1m3 of the material).

Where:

▪ F is the applied force,
▪ e is extension obtained at force F,
▪ A is the area of the cross section of the object and
▪ l is the length of the object

With the knowledge of ρε we can calculate the total energy stored in an object (i.e. that given by the area under the force - extension graph) if we know the volume of the object.

We can demonstrate this by calculating the work done per unit volume from the total work (W) done on the object derived from the force - extension graph.

#BeBrainly

Answer 2

it is fixed by its theorem for ex - in maths 90-1/2 angle A = exterior angle it is an theorum