Chapter 11, Problem 63P

Pulsars—the rapidly rotating neutron stars described in Example 11.2—have magnetic fields that interact with charged particles in the surrounding interstellar medium. The result is torque that causes the pulsar’s spin rate and therefore its angular momentum to decrease very slowly. The table below gives values for the rotation period of a given pulsar as it’s been observed at the same date every 5 years for two decades. The pulsar’s rotational inertia is known to be 1.12 × 10³⁸ kg · m². Make a plot of the pulsar’s angular momentum over time, and use the associated best-fit line, along with the rotational analog of Newton’s law, to find the torque acting on the pulsar.

Year of observation	1995	2000	2005	2010	2015
Angular momentum (l037 kg · m2/s)	7.844	7.831	7.816	7.799	7.787