Xavier is roller skating at 14 km/h and tosses a set of keys on the ground at 8 km/h. the speed of the keys relative to the ground is km/h.

The speed of the keys with respect to the ground is given by:

Where,

Vk-s: Speed of the keys with respect to the skater

Vs-g: Speed of the skater compared to the ground

Substituting values in the equation we have:

The speed of the keys relative to the ground is 22 km / h.

blue light is scattered in different directions by the tiny molecules of air. blue is scattered more than other colours because it has a shorter distance to travel which results in smaller waves. this is why we see a blue sky most of the time.