What is the kinetic energy of a 2 kg mass moving at 3 m/s?

What is the kinetic energy of a 2 kg mass moving at 3 m/s?

• A. 3 J
• B. 12 J
• C. 9 J
• D. 6 J

Answer: (C)

Kinetic energy is 1/2 m v^2, so it depends on both how heavy the object is and how fast it’s moving. With a mass of 2 kg and a speed of 3 m/s, square the speed to get 9. Multiply by the mass: 2 × 9 = 18. Take half of that: 18 × 1/2 = 9. So the kinetic energy is 9 joules. This shows why speed has a strong effect: energy grows with the square of velocity, so even modest increases in speed can noticeably raise the energy of motion.

Kinetic energy is 1/2 m v^2, so it depends on both how heavy the object is and how fast it’s moving. With a mass of 2 kg and a speed of 3 m/s, square the speed to get 9. Multiply by the mass: 2 × 9 = 18. Take half of that: 18 × 1/2 = 9. So the kinetic energy is 9 joules. This shows why speed has a strong effect: energy grows with the square of velocity, so even modest increases in speed can noticeably raise the energy of motion.