An 800-kg car moving at 80 km/h overtakes a 1200-kg car moving at 40 km/h in the same direction. If the two cars stick together, the wreckage has an initial speed of

Question

Quizplus · Accepted Answer

To solve this, we use the principle of conservation of momentum. The total momentum before the collision equals the total momentum after the collision. Let's convert the speeds from km/h to m/s: 80 km/h = 22.22 m/s and 40 km/h = 11.11 m/s. The total momentum before the collision is (800 kg * 22.22 m/s) + (1200 kg * 11.11 m/s) = 17776 + 13332 = 31108 kg*m/s. After the collision, the total mass is 800 kg + 1200 kg = 2000 kg. Using the formula for momentum (p = mv), we find the velocity of the wreckage: 31108 kg*m/s = 2000 kg * v, solving for v gives v = 15.554 m/s. Converting back to km/h (v * 3.6), we get approximately 56 km/h.

An 800-Kg Car Moving at 80 Km/h Overtakes a 1200-Kg