A. Weight because take an example of a lever, say you have a ball on a lever. if you roll the ball to the left, the WEIGHT will bring down the opposite end. hoped this helped :)
In 6 secs, the dog covers- S=vt 8.9*6 = 53.4 m. In the same time, the cat covers, 53.4-3.8 = 49.6 m. Thus, speed of the cat, v= s/t, = 49.6/6 = 8.267 m/s
