Except when necessary for takeoff and landing, <span>the minimum safe altitude required for a pilot to operate an aircraft over other than congested area is an altitude of 1000 ft above the highest obstacle within a 2000 ft horizontal radius of the aircraft.
It is also good to know that apart from taking off and landing, the aircraft must not operate at a distance less than 500 ft from any person, vessel, structure or vehicle.</span>
Electromagnetic radiation
Explanation:
Kinetic energy (J) = 2j
mass= 250g
velocity=?
1kg=1000g
mass= 250/1000
mass=0.25kg
Kinetic energy (J) = ½ x mass (kg) x [velocity]² (m/s)
2=1/2 × 0.25× [velocity]²
2=0.125× [velocity]²
[velocity]² = 2/0.125
[velocity]²=16
velocity= (16)^1/2
velocity= 4 m/s