1. 1a. A ball vertically drops from rest onto a flat surface a distance 3.0\,\mathrm{m}3.0m below the ball. After bouncing once, it returns to its original height. You may assume that the time of the collision is small compared to the total time the ball is moving. How long does it take the ball to reach its original height again after being dropped? Please give your answer in units of \mathrm{s}s. 1.56 2. 1b. What is the velocity of the ball right before the collision? Assume "up" is the positive direction. Please give your answer in m/s. 3. 1c. What is the average acceleration of the ball given that the collision lasts 5 ms? Please give your answer in m/s.