Achild standing on a bridge throws a rock straight down. the rock leaves the child's hand at time t = 0 s. if we take upward as the positive direction, which of the graphs shown below best represents the velocity of the stone as a function of time?

Diego is trying to lift a piano to the second floor of his house. diego uses a pulley system and gives a big lift to the piano. the piano moves upward, then stops, and then it starts to fall to the ground. which list best describes the forces on the piano in the proper order? a.positive force, balanced force, negative force b.negative force, balanced force, positive force c.positive force, unbalanced force, negative force d. negative force, unbalanced force, positive force