Question

A boy tosses a ball straight up with an initial velocity of 13.0m/s a)how long does the ball take to reach its highest point? B)how high does the ball rise above it's realise point

Answer 1

Given,

Initial velocity of the ball (u)=13 m/s

Let the time taken by the ball to reach to highest point be t and the height reached by the ball be H.

At the top most point, the velocity of the ball will be zero, so $v=0$

Gravitational acceleration of the ball $(g)=9.8 m/s^2$

Now, applying the first law of motion,

$v=u-gt$

Now, substituting the values,

$0=13-9.8t$

$\Rightarrow t=\frac{13}{9.8}sec$

Now, applying the third equation of motion,

$v^2=u^2-2gh$

Substituting the values,

$0=13^2-2\times 9.8\times h$

$\Rightarrow h = \frac{13\times 13}{2\times 9.8}m$

$h=8.62m$