A 5 kg object moves with velocity 8 m/s. What is its kinetic energy?

A 5 kg object moves with velocity 8 m/s. What is its kinetic energy?

• A. 160 J
• B. 320 J
• C. 80 J
• D. 100 J

Answer: (A)

Kinetic energy depends on both mass and velocity squared, so the formula is KE = 1/2 m v^2. With a mass of 5 kg and a speed of 8 m/s, plug in the numbers: KE = 0.5 × 5 × (8)^2 = 2.5 × 64 = 160 joules. The 1/2 factor is essential; omitting it would give 320 J, which isn’t correct for this situation. The other options come from using the wrong factor or a different velocity. So the kinetic energy is 160 J.

Kinetic energy depends on both mass and velocity squared, so the formula is KE = 1/2 m v^2. With a mass of 5 kg and a speed of 8 m/s, plug in the numbers: KE = 0.5 × 5 × (8)^2 = 2.5 × 64 = 160 joules. The 1/2 factor is essential; omitting it would give 320 J, which isn’t correct for this situation. The other options come from using the wrong factor or a different velocity. So the kinetic energy is 160 J.