Answer:
1.33 km/s
Step-by-step explanation:
acceleration due to gravity, g = 1.81 m/s²
height, h = 490 km = 490000 m
Let u is the initial speed and the final speed is zero.
use third equation of motion
v² = u² - 2 g h
0 = u² - 2 x 1.81 x 490000
u² = 1773800
u = 1331.84 m/s
u = 1.33 km/s
Thus, the initial speed of the material is 1.33 km/s.