Problem: the article describes the different between a crash with no helmet and a crash with a helmet. based on the article, 1) determine the impulse of a crash with a helmet (assume the force is 45 n) and 2) determine the impulse of a crash with no helmet (assume the time of impact is now 1.5 ms and the force is still 45 n). show your work with formula, substitution, and answer with units.

Hey you didn't mention the time of impact for the first condition ?
if you assume having the same impact time then in both the conditions the impulse will be the same 0.0675 NS.
helmets are designed in such a way to negotiate the impact.. by absorbing the energy in their cushion type material, they act like a dissipator, which sucks the impact energy, thus preventing us from getting injuries , both the condition will have same impulse but in first condition the impact will be tremendous as there is no helmet and in second condition the person has helmet so the impact will be less.
•impulse = Force*time
1.5 ms = 0.0015 secs

    5.5 n======    assuming that      we have      m = 0.145 kg    a = 38 m/s²therefore    5.51 n, but two significant figures.final answer: 5.5 n