You want to stop two identical moving objects. object 1 is moving faster than object 2, so it would take more to stop object 1.

force?

maybe, sorry if im wrong

A weight-training program that gradually increases the resistance lifted relies on the progression principle to build strength, where strength is the amount of force a muscle can exert.
The principle of progression states that you should overload gradually and that there is a perfect level of overload in-between a too slow increase and a too rapid increase.