A ball is thrown upward from the top of a 28.2-m-tall building. The ball's initial speed is 10.1 m/s. At the same instant, a person is running on the ground at a distance of 27.3 m from the building. What must be the average speed of the person if he is to catch the ball at the bottom of the building?

If a rock is thrown upward on the planet mars with a velocity of 12 m/s, its height (in meters) after t seconds is given by h = 12t − 1.86t2. (a) find the velocity of the rock after two seconds. m/s (b) find the velocity of the rock when t = a. 12−3.72a m/s (c) when will the rock hit the surface? (round your answer to one decimal place.) t = s (d) with what velocity will the rock hit the surface? m/s