Rate of Change 1. A ball rolling down an incline travels "s" feet in "t" seconds, where s = 5t2. Derive a formula for the velocity of the ball at time t = to. How fast is it going (a) after 2 seconds (b) after it has rolled 80 feet. 2. By definition, acceleration is the rate of change of velocity with respect of time. Find the acceleration of the falling body considered in Example 1. 3. A ball is thrown straight up is located 's" feet above the ground in "t" seconds after it is thrown in accordance with the formula s = 112t - 16t2. Find a formula for the velocity of the ball and find (a) the time required to reach its highest point, (b) the distance of the highest point above the ground, and (c) the acceleration of the ball at this point