A 2035 kg Oldsmobile traveling east on Saginaw Street at 15.8 m/s is unable to stop on the ice covered intersection for a red light at Abbott Road. The car collides with a 4012 kg truck hauling animal feed north on Abbott at 10.5 m/s. The two vehicles remain locked together after the impact. Required:
Calculate the velocity of the wreckage immediately after the impact.

Ithink it’s: light bounce if off a mirror

Sounds propagates through some kind of medium. usually it's air, but it goes just as well through solid objects like walls, windows etc. a soundwave will compress the (air)molecules in front of it, and if this increased density wave hits your ears, you register it as sound. solid objects like walls are a lot denser than air, this means that they will damp a wave, but also carry it easier.