Final answer:
The correct analysis model to describe the spool as the cord is pulled and will be most useful for solving part (b) of this problem is a rigid object under a net torque.
Step-by-step explanation:
The correct analysis model to describe the spool as the cord is pulled and will be most useful for solving part (b) of this problem is d. rigid object under a net torque.
When a net torque is applied to a rigid object, it causes the object to rotate. In this case, as the cord is pulled, a net torque is exerted on the spool, causing it to rotate and unwind the cord. This analysis model takes into account the rotational motion of the spool and is suitable for solving part (b) of the problem.
Let's consider the scenario described in part (b) of the problem where a 40-N weight is used instead of the 40-N force. The angular velocity of the cylinder after 5.0 m of cord have unwound can be calculated using the work-energy theorem, taking into account the change in potential energy and the rotational kinetic energy of the cylinder. Substituting the given values into the appropriate formula will allow for the calculation of the angular velocity.