Respuesta :
The time when the ball hit the ground, which is thrown from a height of 70 meters with an initial downward velocity of 10 m/s is 2.87.
What is a quadratic equation?
A quadratic equation is the equation in which the unknown variable is one and the highest power of the unknown variable is two.
The standard form of the quadratic equation is,
[tex]ax^2+bx+c=0[/tex]
Here,(a,b, c) is the real numbers and (x) is the variable. To solve the equation for x, use the following formula,
[tex]x=\dfrac{-b\pm\sqrt{b^2-4ac}}{2a}[/tex]
The ball's height h (in meters) after t seconds is given by the following.
[tex]h=70-10t-5t^2[/tex]
The ball is thrown from a height of 70 meters with an initial downward velocity of 10 m/s. In this case,
- Height h=70 meters
- Velocity v=10 m/s.
The time when the ball hit the ground has to be find out. The value of the height when it hit the group is zero. Put the value of h=0 in the above equation,
[tex]h=70-10t-5t^2\\0=70-10t-5t^2\\5t^2+10t-70=0\\5t^2+10t-70=0\\[/tex]
Solve the quadratic equation using the following formula,
[tex]t=\dfrac{-10\pm \sqrt{10^2-4(10)(-70)}}{2\times5}\\t=-4.87, t=2.87[/tex]
Consider positive value. Thus, the time when the ball hit the ground, which is thrown from a height of 70 meters with an initial downward velocity of 10 m/s is 2.87.
Learn more about the quadratic equation here;
https://brainly.com/question/1214333
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