Question

A water rocket is projected vertically upward from the ground. Its a height(h) m above the ground after t seconds is given by h=20-5(t-2)^2. When will the rocket reach the ground?
MARKING THE BRAINLIEST

Answer 1

Answer:

after 4 seconds

Step-by-step explanation:

Given

h = 20 - 5(t - 2)²

When rocket is on ground then h = 0

Equate to zero and solve for t

20 - 5(t - 2)² = 0 ( subtract 20 from both sides )

- 5(t - 2)² = - 20 ( divide both sides by - 5 )

(t - 2)² = 4 ( take the square root of both sides )

t - 2 = ± $\sqrt{4}$ = ± 2 ( add 2 to both sides )

t = 2 ± 2

Thus

t = 2 - 2 = 0 ← when rocket is launched

t = 2 + 2 = 4 ← when rocket hits the ground

The rocket reaches the ground after 4 seconds