If the roller coaster leaves point Q from rest, what is its speed at the top of the 25-m peak (point S)?

Velocity=total displacement/timefrom house to store is 500 from store to neighbor is 200 therefore total displacement=500+200=700metrestherefore,700metres/910seconds=0.8metres per second

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.

The law of conservation of momentum will be the same no matter where you apply it.the equation will be  77.4 + m (mass of canister) *3.6