To calculate acceleration force, the relationship F = ma is crucial. Given a force that accelerates 4.5 kg at 40 m/s², it can be used to determine how much acceleration that same force would provide for an 18 kg mass. By rearranging the formula, if m1 is 4.5 kg and a1 is 10 m/s², the force can be calculated as F = (4.5)(10). Using the same force for 18 kg, the acceleration can be found with the equation (4.5)(10) = (18)(a). This method illustrates the fundamental principles of Newton's second law of motion.