The initial kinetic energy of the cart is:
[tex]K_i = \frac{1}{2}mv^2 = \frac{1}{2}(25 kg)(2m/s)^2=50 J [/tex]
where m is the mass of the cart and v its initial speed.
Then, the force F is applied, in the direction of motion of the cart.The work done by this force is:
[tex]W=Fd=(5 N)(6.0 m)=30 J[/tex]
For the work-energy theorem, the work done by the force is equal to the variation of kinetic energy of the cart:
[tex]K_f - K_i = W[/tex]
And so, the final kinetic energy of the cart is
[tex]K_f = K_i + W=50 J+30 J=80 J[/tex]
