Sum the two results to find the total displacement. LEARN MORE Remarks To find the displacement while braking, we could have used the two kinematics equations involving time, namely, Ax = vot + 1/2 at2 and v = vo + at, but because we weren't interested in time, the time-independent equation was easier to use. Ax coasting Question By how much would the answer change if the plane coasted for 2.0 s before the pilot applied the brakes? m PRACTICE IT + Axbraking = 72 m +572 m = 644 m EXERCISE Use the worked example above to help you solve this problem. A typical jetliner lands at a speed of 156 mi/h and decelerates at the rate of (11.3 mi/h)/s. If the jetliner travels at a constant speed of 156 mi/h for 1.1 s after landing before applying the brakes, what is the total displacement of the jetliner between touchdown on the runway and coming to rest? 76.7 X Your response differs from the correct answer by more than 10%. Double check your calculations. m HINTS: GETTING STARTED | I'M STUCK! A jet lands at 18.5 m/s, applying the brakes 1.98 s after landing. Find the acceleration needed to stop the jet within 5.28 x 10 m. -0.324 X You are neglecting some of the given information. The jet must stop within a certain distance after landing, but it does not start slowing down right away. How much distance is left on the runway once the jet starts to slow down? m/s