1. (TCO 5 & 6) A cannon ball is dropped from a building. Suppose that the height of the cannon ball (in meters)
after t seconds is given by the quadratic function
f(t) = -4.4t^2 + 50
Find the average velocity in the time interval [1, 4] seconds.
(Points : 5)
-5.66 m/s
-11.73 m/s
-13.75 m/s
-18.44 m/s
-22 m/s

Question

1. (TCO 5 & 6) A cannon ball is dropped from a building. Suppose that the height of the cannon ball (in meters)
 after t seconds is given by the quadratic function
 f(t) = -4.4t^2 + 50
Find the average velocity in the time interval [1, 4] seconds.
(Points : 5) 
      -5.66 m/s
      -11.73 m/s
      -13.75 m/s
      -18.44 m/s
      -22 m/s

anonymous · Answer

$$v _{avg}=1/2(v _{f} + v _{i})$$
$$v(t)=\frac {df}{dt}=-8.8t$$so the speed at t = 1 sec and t = 4 sec are$$v(1)=-8.8m/s^{2}(1s)=8.8m/s$$and$$v(4)=-8.8m/s^{2}(4s)=-35.2m/s$$plug into equation for v avg$$v _{avg}=1/2(-8.8m/s-35.2m/s)=22m/s$$