Question

If an object is projected upward with an initial velocity of 123 ft per​ sec, its height h after t seconds is h=−16t2+123t. Find the height of the object after 5 seconds.

Answer 1

Answer:

Height after 5 seconds is 215 ft

Step-by-step explanation:

Given that:

The initial velocity of object which is projected upwards is 123 ft/sec.

Height of the object, h after time t in seconds,  is given as:

$h=-16t^2+123t$

Here, t will always be positive, so $123t$ and $16t^2$ will also be positive.

But coefficient of $16t^2$ is negative, that means something is subtracted from the positive term $123t$.

To find:

Height of object after 5 seconds.

Solution:

Given that $t=5$ seconds.

Let us put the value in the given relation of $h$ and $t$:

$h=-16\times 5^2+123 \times 5\\\Rightarrow h=-400+615\\\Rightarrow \bold{h = 215\ ft}$

So, height after 5 seconds is 215 ft.