Erosion is caused naturally by water, wind or gravity, and accelerated erosion is caused by human use of land.
20km every 1 hr is what 20km/hr means.
so 3hrs is 20km*3=60km.
Answer:
The International Space Station move at 7.22 km/s.
Explanation:
Orbital speed of satellite is given by , where G is gravitational constant, M is mass of Earth and r is the distance to satellite from centre of Earth.
r = R + h = 6350 + 1400 = 7750 km = 7.75 x 10⁶ m
G = 6.673 x 10⁻¹¹ Nm²/kg²
M = 5.98 x 10²⁴ kg
Substituting
The International Space Station move at 7.22 km/s.
Gamma rays because it has more penetrating power and frequency but shorter wavelength.