A rocket-propelled sled undergoes a high-speed acceleration test on a straight, horizontal track. As the sled travels, it rapidly consumes its solid rocket propellant. The time taken for the sled to cover successive 100 m intervals is observed to decrease.
The interval times decrease because:
the forward acceleration of the sled increases.
the air resistance acting on the sled decreases.
the maximum speed of the sled increases.
the runners of the sled become hotter, reducing the friction with the track.
