1. The problem statement, all variables and given/known data A person riding in the back of a pickup truck traveling at 70 km/h on a straight, level road throws a ball with a speed of 15 km/h relative to the truck in the direction opposite to the truck's motion. What is the velociy of the ball (a) relative to a stationary observer by the side of the road, and (b) relative to the driver of car moving in the same direction as the truck at a speed of 90 km/h? 2. Relevant equations VBT = 15 km/h VBG = VBT + VTG VBG = 15 km/h + 70 km/h Trying to find the velocity of the ball with respect to the ground (observer) I’m not sure if this is correct but the answer I got was 85 km/h 3. The attempt at a solution My notes in class said add the velocity of the truck with respect to the ground plus the velocity of the ball with respect to the truck to get (a). I'm not sure where to start with (b)?