Answer:
0.98 [sec].
Step-by-step explanation:
1) the time when the player is moving up equals the time the player falls, it can be 't'. Then
2) the equation of moving down can be written as

g=10 [m/s²], t - time, h - the given height.
3) according to the formula above the time spent to moving down is:

![t=\sqrt{(2.4)/(10)}=√(0.24) =0.49[s].](https://img.qammunity.org/2023/formulas/physics/college/qu53daunm32dpfhbg6oeyuzjapn0ld5j0o.png)
4) finally, the total time is t*2=0.98[sec].