Question

a bullet of mass 15 gm has a speed of 400 m/s.what is its kinetic energy

Answer 1

mass = m = 15 g = 0.015 kg
speed = v = 400 m/s
kinetic energy = 1/2 m v ² = 1/2 × 0.015 × 400² = 1/2 × 0.015 × 400 × 400 = 1200 joules

Answer 2

Mass= 15 gm = .015 kg
v=400m/s
Now kE=1/2 × .015 × 400 × 400
= 2×40× 15
= 1200 J ans