Airplane flight recorders must be able to survive catastrophic crashes.

Airplane flight recorders must be able to survive catastrophic crashes. Therefore, they are typically encased in crash-resistant steel or titanium boxes that are subjected to rigorous testing. One of the tests is an impact shock test, in which the box must survive being thrown at high speeds against a barrier. A 41-kg box is thrown at a speed of 205 m/s and is brought to a halt in a collision that lasts for a time of 6.5 ms. What is the magnitude of the average net force that acts on the box during the collision?

From Newton's second law, the impact on the box is
Ft = m(change in velocity)
where F is the net force, t is time of impact, m is mass of the box.
Thus, F = m(change in velocity)/t
= 41(205 - 0)/6.5E-3
= 1293000N