Solving Quadratic Equations in the Real World

If I want to find out when an object hits the ground, I should _________.

• Use x = (-b/2a) as my answer.
• Set my equation = 0 and solve.
• Replace x with 0 and evaluate.
• Find the y-coordinate of the vertex.

Mrs. Martone's 7th grade science class built and launched rockets. The graph below shows the height, in feet, over time, in seconds, of a student's rocket. Use the graph to answer the questions below. How long was the rocket in the air?

• 1 second

• 7 seconds

• 14 seconds

Mrs. Martone's 7th grade science class built and launched rockets. The graph below shows the height, in feet, over time, in seconds, of a student's rocket. Use the graph to answer the questions below. What is the height of the rocket at 5 seconds?

• 30 feet

• 60 feet

• 65 feet

• 70 feet

• 24 feet

• 10 feet

• -4 feet

• 3 feet

• 3 seconds

• 46 seconds

• 5 seconds

• 10 seconds

• 24 feet

• 9 feet

• 46 feet

• 34 feet

• Between 4 and 5 seconds

• Between 5 and 6 seconds

• Between 6 and 7 seconds

• Between 9 and 10 seconds

• 3 seconds

• 4 seconds

• 3.5 seconds

• 2 seconds

An object in launched directly upward at 64 feet per second (ft/s) from a platform 80 feet high. Its height is represented by the equation

s(t) = –16t² + 64t + 80

What will be the object's maximum height?

• 2 ft

• 80 ft

• 144 ft

• 64 ft

You jump off a 24 foot high cliff and your fall is modeled by the function:

h(t) = -16t² + 8t + 24

How long would it take you to hit the water?

• 8 seconds

• 1 second

• 1.5 seconds

• 1/4 second