Vector Nature of Newton’s 2 nd Law of Motion and Newton’s 3 rd Law

Vector Nature of Newton’s 2nd Law of Motion and Newton’s 3rd Law 4.4 and 4.5

4.4 Vector Nature of Newton’s 2nd Law of Motion • Vectors – F, a, v • Use components – x and y • Rewrite 2nd law • Fx = max • Fy = may

Example 1 • An 10,000-kg airplane is pointing north and applying 3,000 N of thrust. The wind is blowing west and applying a 1,500-N force on the plane. Ignoring air-resistance, was is the magnitude of the x and y components of the resultant acceleration? • ax = -6.67 m/s2 • ay = 3.33 m/s2

Example 2 • If the airplane in the previous problem was traveling 200 m/s due north when the wind started blowing, what was its displacement after 1 minute? • x = -12000 m • y = 18000 m

4.5 Newton’s 3rd Law of Motion • You have a car crash • Other car hits you, so your car crunched • Why other car crunched too?

Newton’s 3rd Law of Motion • Whenever one body exerts a force on a second body, the second body exerts an equal and opposite force. • Every action has equal and opposite reaction

Acceleration due to the 3rd Law • A 70-kg diver jumps off a boat on a smooth lake. He applies 75 N horizontally against the 500-kg boat. What are the accelerations of the diver and the boat? • ad = 1.07 m/s2 • ab = -0.15 m/s2

Practice Work • Try • 115 #CQ6 – 8, P10 – 14, 16 • Total of 9 problems

Vector Nature of Newton’s 2 nd Law of Motion and Newton’s 3 rd Law