After the start of the study, the Principal Investigator reports to the IRB that, as expected, one of the children became upset. The incident was handled according to the protocol and the child is fine. What should the IRB do with regard to this report?

Nothing

Explanation:

When judgements or researchs are carried out, they are done in consideration of an overall sample,and not just in the favour of someone out of all the sample considered. Judging or concluding from an individual would be bias and won't give a fair result. As the IRB has carried out the investigation and has decided the results, the expression of a child should not affect their decision.

we can solve this via the kinematic equation:

where the vertical velocity is zero and so:

since the height of the building is 29.3 meters then:

the ball was in motion for approximately 2.45 seconds

answer; taking detailed notes during the interview;