Which statement is true for a car that first goes around a curve of radius r at a constant speed v, and then goes around the same curve at half the original speed? a. the centripetal force is twice as big the second time around. b.the centripetal force is four times as big the second time around. c.the centripetal force is one-half as big the second time around. d.the centripetal force is one-fourth as big the second time around.

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.