Where is old crust melted back into magma

Which statement is true for light passing into a medium that is more optically dense than the first medium through which it past

Acar moves at 12m/s and coasts up a hill with a uniform acceleration of -1.6m/s2. how far has it traveled after 6.0s?

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?