Question

If a certain cannon is fired from a height of 9.8 meters above the​ ground, at a certain​ angle, the height of the cannonball above the​ ground, h, in​ meters, at​ time, t, in​ seconds, is found by the function h(t) = -4.9t² + 30.5t +9.8. Find the time it takes for the cannonball to strike the ground.

Answer 1

Answer:

6.53 s

Step-by-step explanation:

The height of the cannon ball is represented by a quadratic function as:

h(t) = -4.9t² + 30.5t +9.8.

At 0 s (i.e. t = 0), h(0) = -4.9(0²) + 30.5(0) + 9.8 = 9.8

That means that the cannon ball is initially at a height of 9.8 m above the ground. To calculate the time it takes the ball to touch the ground, we use:

h(t) = -4.9t² + 30.5t +9.8

It touches the ground when h(t) = 0. Hence:

0 = -4.9t² + 30.5t + 9.8

Solving the above quadratic equation gives:

t = 6.53 s and t = -0.31 s

Since the time cannot be negative, hence t = 6.53 s. Therefore it takes the ball 6.53 s to hit the ground.