Question 917284
h= -16t^2+1000 t+50 
if h= 2000 ft
then 2000 = -16t^2+1000t +50
 *[invoke explain_simplification "2000 = -16t^2+1000t +50" ]

hence after 2 seconds or 60 seconds it will reach 2000 ft ------statement1

when h =2000 ft+2000 ft  ( further 2000 ft)
 4000 =-16t^2+1000t +50
*[invoke explain_simplification "4000 =-16t^2+1000t +50" ]

Hence after 4 seconds or 58 seconds it will further reach 2000 ft....statement 2

from above statements it is concluded that first 2000 ft will be reached in 2 seconds and further 2000 ft will reached in 4 seconds