A girl is riding her scooter and finds that its speedometer reading is constant. Is it possible for her scooter to be accelerating and if so, how?

Yes, it is possible for the scooter to be accelerating even if the speedometer reading is constant. A speedometer shows only the speed of the scooter, not its direction. Acceleration occurs whenever there is a change in velocity, and velocity depends on both speed and direction. If the girl is riding the scooter along a curved path or taking a turn, the direction of motion changes continuously even though the speed remains constant. Due to this change in direction, the velocity changes and the scooter is said to be accelerating. Thus, a body moving with constant speed can still have acceleration if its direction of motion changes.