Question

a volleyball player has spiked the ball. At the instant the ball leaves her hand, it is 2.6 m above the ground and has an initial vertical velocity of -20 m/s. How long will it take the ball to strike the ground if the opposing team doesn't block it?

Answer 1

Answer: 29.48 s

Step-by-step explanation:

Given

The initial height of the ball is
`h=2.6\ m`

The ball leaves with an initial velocity of
`u=-20\ m/s`

Using the equation of motion

`h=ut+(1)/(2)at^2\\\text{Insert the values}\\\\2.6=20\cdot t+(1)/(2)* 9.8* t^2\\\\\Rightarrow 9.8t^2+20t-5.2\\\\\Rightarrow t=(-20\pm √(20^2-4* 9.8* (-5.2)))/(2* 9.8)\\\\\Rightarrow t=(-20\pm 603.84)/(19.8)\\\\\Rightarrow t=29.48\ s\quad [\text{Neglecting negative t}]`

Therefore, it take 29.48 s for ball to reach the ground.