Question

A golfer hits a ball from a starting elevation of 4 feet with a velocity of 70 feet per second down to a green with an elevation of −5 feet. The number of seconds t it takes the ball to hit the green can be represented by the equation −16t2 + 70t + 4 = −5. How long does it take the ball to land on the green?

Answer 1

t = 4.5 seconds

Explanation:

It is given that, a golfer hits a ball from a starting elevation of 4 feet with a velocity of 70 feet per second down to a green with an elevation of −5 feet.

The number of seconds t it takes the ball to hit the green can be represented by the equation as follows :

`-16t^2 + 70t + 4 = -5\\\\-16t^2 + 70t + 9=0`......(1)

We need to find time taken by the ball to land on the green. Solving the quadratic equation (1) we get :

t = -0.125 s and t = 4.5 s

Ignoring t = -0.125 s, we get the time taken by the ball to land on the green is 4.5 seconds.