1. In 10 seconds a car accelerates 4m/s? to 50 m/s.
How fast was the car going before it accelerated?
2.
Variables:
Equation and Solve:

In 10 seconds a car accelerates 4m/s2 to 50 m/s. How fast was the car going before it accelerated?

2. they have negligible mass.

Rain is pulled by gravity which is a non contact force

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.