Two 0.006 Kg bullets are fired with speeds of 20.0 m/s and 50.0 m/s respectively. What are their kinetic energies? Which bullet has more kinetic energy? What is the difference of their kinetic energies?

a) Kinetic energies

K₁ = 1.2 J

K₂ = 7.5 J

b) The bullet that has the highest kinetic energy is the one with the highest speed, v = 50 m/s, K₂ = 7.5 J

c) K₂ - K₁ = 6.3 J

Explanation:

The kinetic energy (K) is that due to the movement of a body and is calculated as follows:

K = (1/2) m*v² (J)

Where:

m : the mass of the body (kg)

v is the speed of the body (m/s)

Data

m₁ = m₂ = 0.006 Kg

v₁ = 20 m/s

v₂ = 50 m/s

a) Calculation of the kinetic energy

K₁ = (1/2) (m₁) * (v₁) ²

K₁ = (1/2) (0.006) * (20) ²

K₁ = 1.2 J

K₂ = (1/2) (m₂) * (v₂) ²

K₂ = (1/2) (0.006) * (50) ²

K₂ = 7.5 J

b) K₂ ˃ K₁

The bullet that has the highest kinetic energy is the one with the highest speed, v = 50 m/s, K₂ = 7.5 J

c) Difference of their kinetic energies (K₂ - K₁)

K₂ - K₁ = 7.5 J - 1.2 J = 6,3 J