Chapter 4, Problem 78PP

Laptop computers are equipped with accelerometers that sense when the device is dropped and then put the hard drive into a protective mode. Your computer geek friend has written a program that reads the accelerometer and calculates the laptop’s apparent weight. You’re amusing yourself with this program on a long plane flight. Your laptop weighs just 5 pounds, and for a long time that’s what the program reports. But then the “Fasten Seatbelt” light comes on as the plane encounters turbulence. For the next 12 seconds, your laptop reports rapid changes in apparent weight, as shown in Fig. 4.29.

FIGURE4.29 The laptop’s apparent weight (Passage Problems 76-79).

During interval C, you can conclude for certain that the plane is

1. a. at rest.
2. b. accelerating upward.
3. c. accelerating downward.
4. d. moving with constant vertical velocity.