Question

A train engine weighs 4 times that of a railroad car. the engine collides into the car (initially at rest) and they both stick together. if the speed of the train engine before the collision was 6 km/hr, find the speed of the engine/car system just after the collision.

Answer 1

Using the conservation of momentum, the final velocity of the train engine and railroad car system, after the collision where they stick together, is found to be 4.8 km/hr.

Step-by-step explanation:

The student's question involves the concept of conservation of momentum, which is a fundamental principle in physics. When a train engine collides with a railroad car and they stick together, the speed of the combined system just after the collision can be calculated using this principle.

To find the speed just after the collision, we can set up the equation for the conservation of momentum as follows: (mass of engine × velocity of engine before collision) + (mass of car × velocity of car before collision) = (combined mass of engine and car) × (velocity of combined system after collision).

Let m be the mass of the railroad car, then the mass of the engine is 4m. The velocity of the car before collision is 0 km/hr (since it’s at rest). Plugging in values, we get:
4m × 6 km/hr + m × 0 = (4m + m) × v, where v is the velocity of the combined system. Simplifying, we find that the final velocity, v, of the combined system is 4.8 km/hr.