1. Newton’s Second Law of Motion if the net external force of an object is not zero, the object accelerates in the direction of the net force the magnitude of the acceleration is proportional to the magnitude of the net force (i.e. increase force, increase acceleration) and inversely proportional to the objects mass (i.e. increase mass, decrease acceleration) F net is the total of all forces acting on one object directly related to acceleration i.e. +ve net force = +ve acceleration F net = ma Net Force Simulator Newtons Second Law Video

2. Ex. 1 A curler exerts an average force of 9.5 N [S] on a 20 kg stone. Assume the ice is frictionless. The stone started from rest and was in contact with the girl’s hand for 1.86 s. (a) Determine the acceleration of the stone. [S] = + F a = 9.5 N m = 20 kg F net = ? a = ? F net = F a = ma 9.5 = (20)a a = 0.475 m/s 2 (b) Determine the velocity of the stone when the curler released it v 1 = 0 a = 0.475 m/s t = 1.86 s v 2 = ? v 2 = v 1 + at = 0 + (0.475)(1.86) = 0.8835 ∴ the final velocity was 0.9 m/s [S]

3. Ex. 2 A 6.0 kg object experiences an applied force of 4.4 N [E] and an opposing frictional force of 1.2 N [W]. Calculate the acceleration of the object. [E] = + F a = 4.4 N F f = -1.2 N F net = ? F net = F a + F f = 4.4 + (-1.2) = 3.2 F net = 3.2 N m = 6 kg a = ? F net = ma 3.2 = 6a a = 0.5333 ∴ the acceleration of the object was 0.53 m/s 2 2.4 Prac. #1-6 UC #1-3