Give at least two practical examples where knowledge of viscosity is important?

In oil cars and in cosmetics

Explanation:

In oil cars, viscosity is important because at different kilometers the viscosity of car oils need to be less, in that way the engine can work better.

In cosmetics, if you want to take off the color of your face, you need some products to clean it. In that case, viscosity in products is important, if you use crayon like cosmetics, you need a clean product with higher viscosity.

it would be a gas formation