Answer;
= -2.62 cm/s
Solution;
Assuming a constant acceleration (0):
v = gradient of a displacement-time graph where displacement is on the y-axis and time is on the x- axis
v = (x2 - x1)/(t2 - t1)
v = (-4.2 - 3.4)cm/(6.1 - 3.2)s
v = -7.6cm/2.9s
v = -2.62cm/s (rounded to 2 decimal places)