2 in a straight line is given by s a Find the average velocity in ft s over each time interval 1 4 8 3 ii 6 8 2 iii 8 10 0 iv 8 12 1 ft s ft s S ft s ft s b Find the instantaneous velocity in ft s when t 8 X ft s 9t 18 where t is measured in seconds c Draw the graph of s as a function of t and draw the secant lines whose slopes are the average velocities in part a Then select the graph of s with the tangent line whose slope is the instantaneous velocity in part b S