Question

An arrow is shot vertically upward at a rate of 240 feet per second from ground level. Use the projectile formula to determine when the arrow hit the ground.

Answer 1

Answer:

After 14.92 seconds, the arrow hits the ground.

Step-by-step explanation:

Given:

Initial velocity of the arrow is, $u=240\ ft/s or 73.152\ m/s$

The arrow goes up and come back to the same starting position. So, initial position is same as that of final position.

Therefore, displacement of the arrow is 0 m.

The displacement of the arrow is given as:

$s=ut-\frac{1}{2}gt^{2}$   (equation 1)

Plug all value in equation 1 and solve for $t$

$0=73.152\timests t-\frac{1}{2} \times9.8 \times t^{2}$

$0=73.152\timests t-4.9 \times t^{2}$

$0=t(73.152-4.9 \times t)$

$73.152-4.9\times t=0$     where $t\neq 0$

$4.9\times t=73.152$

$t=\frac{73.152}{4.9}= 14.92\ s$

∴ After 14.92 seconds, the arrow hits the ground.