In which of the following situations do unbalanced forces act? a. A car travels 20 meters per second, and the driver steps on the brake. b. A chair is dragged across a floor at constant velocity. c. A plane makes a turn at a constant speed. d. An object is dropped vertically toward the ground.
a. A car travels 20 meters per second, and the driver steps on the brake.
d. An object is dropped vertically toward the ground.