Question

Thomas the giant gorilla stood on a bridge 624 feet above the water below. He picked up a car threw it off the bridge with an initial velocity of 50 feet per second. How long will it take the car to splash into the water below?

Answer 1

Answer:

8

Explanation:

Answer 2

Answer:

The car will take approximately 4.865 seconds to splash into the water.

Explanation:

Let suppose that car moves initially downwards. We must see the kinematics of the car after being thrown off the bridge, it is quite certain that car experiment a free fall, in which it is accelerated uniformly by gravity. The time spent by the car to splash into the water is obtained from this equation of motion:

$y = y_{o}+v_{o}\cdot t +\frac{1}{2}\cdot g \cdot t^{2}$

Where:

$y$ - Current height, measured in feet.

$y_{o}$ - Initial height, measured in feet.

$v_{o}$ - Initial velocity, measured in feet per second.

$t$ - Time, measured in seconds.

$g$ - Gravitational acceleration, measured in feet per square second.

If we know that $y = 0\,ft$, $y_{o} = 624\,ft$, $v_{o} = -50\,\frac{ft}{s}$ and $g = -32.174\,\frac{ft}{s^{2}}$, this quadratic function is obtained:

$-16.087\cdot t^{2}-50\cdot t +624 = 0$

Now we get the roots of the polynomial by Quadratic Formula:

$t_{1} \approx 4.865\,s$, $t_{2} \approx -7.973\,s$

Only the first root is physically reasonable. In a nutshell, the car will take approximately 4.865 seconds to splash into the water.