The height of an object t seconds after it is dropped from a height of 550 meters is $s ( t ) = - 4.9 t ^ { 2 } + 550$. Find the average velocity of the object during the first 7 seconds.
A) $\quad 34.30 \mathrm {~m} / \mathrm { sec }$
B) $- 34.30 \mathrm {~m} / \mathrm { sec }$
C) $- 49.00 \mathrm {~m} / \mathrm { sec }$
D) $49 \mathrm {~m} / \mathrm { sec }$
E) $- 16.00 \mathrm {~m} / \mathrm { sec }$

Question

Quizplus · Accepted Answer

The average velocity is calculated as the change in position divided by the change in time. The position at $t = 0$ is 550 meters, and at $t = 7$, it is $-4.9(7)^2 + 550$. The average velocity is $\frac{s(7) - s(0)}{7 - 0} = \frac{-4.9(49) + 550 - 550}{7} = \frac{-240.1}{7} = -34.30 \mathrm{~m/s}$.

The Height of an Object T Seconds After It Is s(t)=−4.9t2+550s ( t ) = - 4.9 t ^ { 2 } + 550s(t)=−4.9t2+550

The Height of an Object T Seconds After It Is $s ( t ) = - 4.9 t ^ { 2 } + 550$