Respuesta :

we use the kinematic equation Δy = v 0 t + 1/2at 2 first to determine the height of fall at 2 seconds.

at t = 2
 
Δy = 1/2a*4 ;  a= 9.81 m/s2
Δy = 19.62 m. 


we then use this data to compute another velocity
v 2 =2aΔx ;
v2 = 2*9.81*19.62
v = 19.62 m/s/