Question

Calculate the kinetic energy of a 100.0-kg meteor approaching the Earth at a speed of 10.0 km/s. Remember that 1 km = 1000 m.

Answer 1

KE=1/2 x mass x speed^2
Substitute:

KE=1/2 x 100 x 10000^2
5000000000J of KE
So either 5 gigajoules
Or 5x10^9J

Answer 2

Kinetic Energy = (1/2) (mass) (speed squared)

Mass = 100 kg
Speed = 10 km/s = 10,000 m/s
Speed squared = 100,000,000 m²/s²

1/2 (M)(V²) = 1/2 (100) (100,000,000) = 5,000,000,000 joules (5 x 10⁹ J)

That's 5 billion joules.

That's the amount of energy a 100-watt light bulb uses in 579 days.