Bench Press: Newton's Second Law of Motion image courtesy ofhttp://www.predatornutrition.com/en/content/exercise-tutorial-how-to-perform-the-perfect-bench-press/ The classic bench press takes place on a flat bench with the bar being lifted straight up from the chest.  When lifting the bar, there is a resistance against your chest muscles that makes it difficult.  To measure this resistance we must look at Newton's Second Law of Motion, F=ma.  F being force acting on the object, m being mass of the object, and a being acceleration of the object.  But how could the bar be heavy when it is not moving?  This is due to the acceleration of gravity.  Gravity is consistently pushing objects toward the center of the earth at an acceleration of about 9.81 meters per second squared.  So to lift 50 kg (110 lbs), you would need to exert (50 kg * 9.81 m/s^2 =) 490.5 Newtons to lift the weight. Home    Squat    Curl    Deadlift    Treadmill    Bibliography