A huge block of white chocolate is being lifted by a cable, which is passed over a pulley and attached to the back of a pickup truck. The pulley is 6m above the ground, and the cable is attached to the truck 1m above the ground. The truck starts out directly below the pulley and pulls forward at 0.25m/s. How fast is the chocolate block rising when the truck has moved 4m? Give your answer to two decimal places