Reading Passage Problems Professor tests airplane takeoff speed D. A. Ward...

Reading Passage Problems

Professor tests airplane takeoff speed D. A. Wardle, a professor of physics from the University of Auckland, New Zealand, tested the takeoff speed of a commercial airliner. The pilot had insisted that the takeoff speed had to be 232 km/h.¹ To perform the testing experiment, Wardle used a pendulum attached to stiff cardboard (Figure 3.16). Prior to takeoff, when the plane was stationary, he marked the position of the pendulum bob on the cardboard to provide a vertical reference line (the dashed line in Figure 3.16). During the takeoff, he recorded the position of the bob at 5-s intervals. The results are shown in the table.

¹The information is taken from the article by D. A. Wardle “Measurement of a eroplane takeoff speed and cabin pressure” published in The Physics Teacher, 37 410–411 (1999).

Using these data, Professor Wardle determined the acceleration at takeoff to be greater than g>4. Then he plotted an acceleration-versus- time graph and used it to find the takeoff speed. It turned out to be about 201 km/h. He was very satisfied—the day was

windy, and the speed of the breeze was about 15–20 km/h. Thus the takeoff speed predicted by his simple pendulum was 215–220 km/h, very close to what the pilot said.

Approximately when did the peak speed occur?

(a) 25 s (b) 20 s (c) 10 s (d) 5 s