The rocket will reach the ground after 4 seconds
Step-by-step explanation:
- Step 1: Find the time when the water rocket reaches the ground.
When the water rocket reaches the ground, the height, h will be zero.
⇒ h = 20 - 5(t - 2)²
⇒ 0 = 20 - 5(t - 2)²
⇒ 5 (t - 2)² = 20
⇒ (t - 2)² = 4
⇒ t - 2 = √4 = 2
∴ t = 2 + 2 = 4 seconds
