C. Insulator
It COULD be semi-insulator but i'm sure its C
The train’s average speed is 80km/h
They can either cancel each other or add up to a resultant force with a certain direction and modulus.
Newton's second law states that F=m*a, where F is the resultant force, ie ΣF.
The North Star, or Polaris, is the brightest star in the constellation Ursa Minor, the little bear (also known as the Little Dipper). As viewed by observers in the Northern Hemisphere, Polaris occupies a special place