1. which of the following causes physical erosion?

a. rivers
b. carbon dioxide
c. oxygen
d. forest fires

2. which of these is still affecting north america geologically, although it ended 10,000 years ago?

a. an earthquake
b. the last glaciation
c. a major subsidence
d. chemical erosion of the grand canyon

3. what caused the formation of the grand canyon?

a. continental drift
b. subsidence
c. physical erosion
d. a tsunami

First answer marked as brainiest which is the correct equation describing the first law of thermodynamics? a) when the internal energy of a system changes, it equals the amount of heat added plus the work done. b) when work is done by the piston, it is equal to the heat added plus the change in internal energy of the system. c) when heat is added to the system, it is equal to the amount of work done by the piston plus the change in internal energy of the system.