Question #4f1eb

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Answer 1 · 2017-02-24T14:29:50

Explanation:

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We know the ball is thrown upwards in a initial velovity of $15.8 m/s$

So, $u=15.8 m/s$

When the ball reaches its maximum height, it has a velocity of $0 m/s$

So, $v=0 m/s$

Let the maximum height be $x$

The gravitational force that makes the ball slow down till it reaches its maximum height

So, $a=-9.8 m/s$

Now, we have to find the time to reach its maximum height

We have our values

$color(orange)(u=15.8 m/s$
$color(orange)(v=0 m/s$
$color(orange)(a=-9.8 m/s$

We can use one of the Kinematic equations

$color(blue)(v=u+at$

$rarr0=15.8+(-9.8t)$

$rarr0=15.8-9.8t$

$rarr9.8t=15.8$

$rarrt=15.8/9.8$

$color(green)(rArrt=1.61 s$

We can use this value to find the maximum height ( $x$ ) using another Kinematic equation

$color(brown)(x=ut+1/2at^2$

$rarrx=(0*1.61)+(1/2*(-9.8)*1.61^2)$

$rarrx=1/2*(-9.8)*2.59$

$rarrx=(-9.8)*1.29$

$color(green)(rArrx=-12.64m$

As height cannot be negative, $x=12.64m$

Hope this helps! :)