Given a force of 10n and an acceleration of 5m/s2 . what is the mass?

Newton's second law of motion:

                               Force  =  (mass) x (acceleration)

                                  10 N  =  (mass) x (5 m/s²)

Divide each side
by  5 m/s²:           10 N / 5 m/s²  =  mass

                                 2 kg  =  mass

Kinetic energy = 1/2mv^2. since the mass is constant we can form a ratio of it's kinetic energy at 60 divided by that at 30 to see ke(60)/ke(30) = +(60^2)/30^2). this may be said to 300% increase.