If a ball is thrown into the air with an initial velocity of 48 ft/s, its height in feet after t seconds is given by y = 48t - 16t2. (a) Find the average velocity of the ball (in ft/s) for the time interval beginning at t = 2 and lasting for each of the following. (1) 0.5 seconds 40 x ft/s (ii) 0.1 seconds 17.6 (iii) 0.05 seconds 16.8 (iv) 0.01 seconds 16.16 x ft/s x ft/s x ft/s (b) Use your answers from part (a) to estimate the instantaneous velocity (in ft/s) when t = 2. 16 X ft/s Enhanced Feedback Please try again. When calculating the average velocity, you are actually calculating the slope of the secant line between the two given points difference in height between the given times, and divide by the change in time. To estimate the instantaneous velocity, look at what the average velocity approaches as the time difference gets smaller. Need Help?