A 747 jetliner lands and begins to slow to a stop as it moves along the runway. The mass is 3.1 105 kg, its speed is 25.5 m/s, and the net braking force is 4.24 105 N.(a) What is its speed 7.45 s later?How far has it traveled in this time?

Question

A 747 jetliner lands and begins to slow to a stop as it moves along the runway. The mass is 3.1  105 kg, its speed is 25.5 m/s, and the net braking force is 4.24  105 N.(a) What is its speed 7.45 s later?How far has it traveled in this time?

Henry · Answer

a. ma, a = F/m = -.24*10^5 / 3.1*10^5 = -.37m/s^2. Vf = Vo + at, Vf = 25.5 -1.37*7.45 = 15.29m/s. b. d = (Vf^2 - Vo^2) / 2a, d = ((15.29)^2 - (25.5)^2) / -2.74 = 152m.