Achemical property is a change in a density b composition of matter c hardness d physical state

Ineed asap! list 3 examples in which friction us or makes things easier in our daily life. explain the effect of friction for each. *make sure you explain the effect of friction for each example! *

Light from the sun reaches the earth in 8.3 minutes. the velocity is 3.00 x 10^8 m/s. how far is earth from the sun? i know how to get to d = (3 x 10^8 m/s)(498 sec). i just don't know how to get from there to the answer being 1.5 x 10^11 m.

Erosion of the beach is normally a slow process. however, in certain situations, large chunks of shore may wash out to sea. what could cause this to happen?