A car rounds a flat curve and experiences a centripetal force directed toward the center of the curve and perpendicular to the direction of its motion. If the driver of the car doesn't hit the brake OR the gas, how will the curve affect the motion of the car?

A) The car's speed and direction will remain constant.
B) The car will speed up and its direction will change.
C) The car will slow down and its direction will remain constant.
D) The car's speed will remain constant and its direction will change.

A dynamic cart moving at 4 m/s is run into the back of and sticks to an identical cart. At what speed should the two carts move off together?
A) 2 m/s
B) 4 m/s
C) 8 m/s
D) It cannot be determined with knowing the actual mass of the carts.