Question

How long will a ball thrown up in the air (without air resistance) with a speed of 60 m/s be in the air until it comes back down.

Answer 1

Using the kinematics formula,

`\begin{gathered} v=u+at \\ u=60m/s^{} \\ a=-9.8m \\ v=0\text{ m/s} \\ 0=60-9.8t \\ -60=-9.8t \\ t=(-60)/(-9.8) \\ t=6.12244897959\approx6\text{ secs} \end{gathered}`

The ball will reach the maximum height at 6 seconds and also takes another 6 seconds to come down after reaching its maximum height.

total time taken = 6 + 6 = 12 seconds