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30. A 1.5 × 103 kg truck moving at 15 m/s strikes a 7.5 x 102 kg automobile stopped at a traffic light. The vehicles hook bumpers and skid together at 10.0 m/s. What is the decrease in kinetic energy?​



Answer :

MathPhys

Answer:

56 kJ

Explanation:

Kinetic energy is the energy stored in a moving body. It is equal to half the mass times the square of the speed (KE = ½ mv²). The change in kinetic energy of the system is therefore:

ΔKE = KE − KE₀

ΔKE = ½ (m₁ + m₂) v² − ½ m₁ u²

ΔKE = ½ (1.5×10³ kg + 7.5×10² kg) (10.0 m/s)² − ½ (1.5×10³ kg) (15 m/s)²

ΔKE = 112,500 J − 168,750 J

ΔKE = -56,250 J

ΔKE ≈ -56 kJ

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