CALC A bird is flying due east. Its distance from a tall building is given by x(t) = 28.0 m + (12.4 m/s)t – (0.0450 m/s3)t3. What is the instantaneous velocity of the bird when t = 8.00s?

Solution 8E The instantaneous velocity of the bird is given by Now in the problem the position is given by . Differentiating the above equation with respect to t we get Now putting the given value of t in the above equation we have So the instantaneous velocity of the bird at t = 8.00 s is 13.5 m/s.