I am trying to post a science/physics question of varying difficulty each week for this year, and maybe a monthly question of greater complexity.

The Rules are:
Answers must be complete, and each statement must be sound/logical.

More than one answer can exists, until its proven false. Hypothesis and theory varies, but scientific logic used must be sound. For example, no marks for cyclic logic. Another example, in cause and effect, no marks for declaring a cause without completely deriving that cause from a generally known and proven fact.

The better the answer, then the more points awarded. Answers can always be updated at anytime as we learn something new everyday.
(I do not claim to have THE answer. I will just attempt to provide a possible answer)

The greater the difficulty, the greater the points. I will give an answer at end of week/month ... hopefully. Repeating my answer awards no points, you will have to come with a better or alternate answer.

I emphasize that Logics is key to getting points aka "Sound logics" aka "there is no other type of logics". It is either logical or illogical. (Some people claim other forms of logic like administrative logistics which they essentially hide some of the steps because such steps are nefarious and then claim that they are using a special type of logics. That will give you zero marks here. Each step must be given) I believe that we are smart people here, so we logically know that "Many people having the same answer" does not automatic conclude, or imply, that that answer is THE answer. What can make an answer THE answer is sound logics and proven experimental tests.)

Using Science and Technology, how would you detect Firearms on people entering thru a private building without being invasive, and given how people generally attire?

A-Level to Tertiary Level Physics
A-Level to Tertiary Level Computer Science
A-Level to Tertiary Level Information Technology

Site share of the week/month
Arvin Ash - YouTube