Difference between solid friction and viscosity is as follows: Viscosity is proportional to the surface area whereas solid friction is independent of area of solid surfaces in contact. Viscous force on the body depends upon its velocity in the viscous media. But, friction does not depend on the velocity of the body.
When light passes through one transparent medium to another transperent medium it bends and that beding of light is know as refraction of light !
The formula is:
v = v o + a t
6 = 10 + 3 * a
3 a = 10 - 6
a = 4 : 3
a = - 1.33 m/s² ( because the car slows down )
Answer: The average acceleration of the car is - 1.33 m/s²