Rafael drops a hard rubber ball, of mass m = 215 g, onto the pavement. He drops it from a height h₁ = 3.1 m, and it bounces back to a height h₂ = 1.95 m. While the ball is in contact with the ground, the ground exerts a non-constant force on the ball as shown in the figure. During the time interval t₁ the force rises linearly to F_max, and during the time interval t₂ the force returns linearly to zero as the ball leaves the ground. Refer to the figure.

For the time intervals t₁ = 3.5 ms and t₂ = 4.5 ms, what is the magnitude of the maximum force between the ground and the ball, in newtons?