Question

Is it possible to crack someone’s car window on the freeway if a popcorn kernel is thrown out of my car window at 80 mph?

Answer 1

Speed of popcorn = 80 mph = 35.763 m/s
Now the mass of the popcorn = 2 g (assume)
Now the initial momentum of the popcorn = (2*10^-3)*(35.763) = 0.0715 kgm/s
Final momentum should be = 0
We know that
Impulse = change in momentum
= 0.0715 - 0 = 0.0715 kg-m/s
Now we know that , Impulse = force*time
if time of contact is very less say in microseconds
F*(10^-6) = 0.0715
F = 71526 N
That means it will be a very huge force so it can be break.
But if contact time is higher in magnitude say 1 s
F*1 = 0.0715
F = 0.0715 N
then it will not break.
So always it depends upon the contact time in which momentum of the particle is becoming zero.