A ball is shot vertically upward from the surface of another planet. A plot of y versus t for the ball is shown in the figure below, where y is the height of the ball above its starting point and t = 0 at the instance the ball is shot. The figure’s vertical scale is set by ys = 30.0 m. (a) Write expressions for the displacement and velocity of the ball as functions of time. (b) What is the magnitude of the free-fall acceleration on the planet? (c) What is the magnitude of the initial velocity of the ball?