Suppose a constant force is the only force applied to an object of unknown mass. what quantities do we need to know in order to find the object's change in momentum? check all that apply. check all that apply. we need to know the change in the position of the object. we need to know the magnitude of the force. we need to know the time interval during which the force acts. we need to know the change in the velocity of the object. impossible: you cannot find the object's change in momentum without knowing its mass.