Calcular la masa de un cuerpo que, estando en reposo, se le aplica una fuerza de 150 N durante 30 seg, permitiéndole recorrer 10 m. ¿Qué rapidez tendrá al cabo de ese tiempo?​

  v = 0.667 m / s,   m = 6746 kg

Explanation:

For this exercise we must use the relationship between work and kinetic energy

          W = ΔK

 the work is defined by

          W = F. x

bold indicates vectors

          W = F x cos θ

in this case the force is in the same direction of displacement

          W = F x    

         F x = K_f - K₀

as the body starts from rest the initial kinetic energy is zero

         F x = ½ m v²

Now let's use the relationship between momentum and momentum

        I = Δp

        I = F t

        Δp = m v_f - m v₀

as part of rest v₀ = 0

        F t = m v

Let's write our system of equations

         F x = ½ m v²

         F t = m v

we have a system of two equations with two unknowns, let's divide the two expressions

         x / t = ½ v

         v = 2x / t

         v = 2 10/30

         v = 0.667 m / s

we look for the mass

         F t = m v

         m = F t / v

         m = 150 30 / 0.667

         m = 6746 kg