Question

A 12000 kg train engine moving at 2.2 m/s hits and locks into 3 boxcars with a total mass of 25000 kg sitting still. If the collision is inelastic and has little friction, how fast will the engine and cars move

Answer 1

Answer: 0.7135m/s

Explanation: M1(mass of the train) = 12000kg

U1(initial velocity of the train) = 2.2m/s

M2(mass of boxcars) = 25000kg

U2(initial velocity of the boxcars which is at rest) = 0

V = common velocity of train and boxcars since the collision was inelastics.

M1U1+M2U2 = (M1+M2)V

12000kg×2.2m/s+25000kg×0m/s = (12000kg+25000kg)V

⇒26400 + 0 = 37000V

V = 0.7135m/s

Answer 2

V = 0.714m/s

Step-by-step explanation:

Full solution calculation can be found in the attachment below.

From the principle of conservation of linear momentum, the sum of momentum before collision equals the sum of momentum after collision.

Before collision only the train had momentum. After the collision the train and the boxcars stick together and move as one body. The initial momentum of the train is now shared with the boxcars as they move together as one body. The both move with a common velocity v.

See the attachment below for the solution calculation.