Newton’s Second Law: The acceleration of an object is proportional to the resultant force acting on the object, and inversely proportional to the mass of the object. As an equation: resultant force = mass × acceleration, F = m a. force, F, in newtons, N; mass, m, in kilograms, kg; acceleration, a, in metres per second squared, m/s². • Students should be able to estimate the speed, accelerations and forces involved in large accelerations for everyday road transport. • Students should recognise and be able to use the symbol that indicates an approximate value or approximate answer, ̃. • Required practical activity 7: investigate the effect of varying the force on the acceleration of an object of constant mass, and the effect of varying the mass of an object on the acceleration produced by a constant force.