Kinetic energy order of magnitude via (1/2)mv² formula

Steps:

• Convert speed: 100 km/h = 100 × (1000/3600) m/s ≈ 27.8 m/s
• Square velocity: v² ≈ (28 m/s)² = 784 m²/s²
• Compute KE: (1/2) × 600 kg × 784 ≈ 300 × 784 = 235,200 J
• Determine order: 2.4 × 10^5 J rounds to 10^5 J magnitude

Why B is correct:

• KE formula yields ~2 × 10^5 J, so order of magnitude is 10^5 J by definition of powers of 10.

Why the others are wrong:

• A: Underestimates by factor of 10, as if speed were ~9 m/s.
• C: Overestimates by factor of 10, as if mass were 6,000 kg.
• D: Overestimates by factor of 100, ignoring proper unit conversion.

Final answer: B