Question

An out-of-control train is racing toward the Metropolis terminal train station - only Superman can help. The train has a mass of 75000 kg, and Superman has a mass of 115 kg. If the train has a velocity of 35 m/s, how fast does Superman have to fly in the opposite direction to stop it in a totally inelastic steel-Man-of-Steel collision?

Answer 1

Answer:

22826.09 m/s

Explanation:

From the law of conservation of momentum,

Sum of momentum before collision = sum of momentum after collision.

For an inelastic collision, the train and the superman have a common velocity

Note: For the superman to stop the train in an opposite direction, the common velocity after collision is zero, and such the total momentum after collision is zero

Therefore,

MU + mv = 0

MU = - mu............................................ Equation 1

Making u the subject of the equation

u = -MU/m......................................... Equation 2

Where M = mass of the train, U = initial velocity of the train, m = mass of the super man, u = initial velocity of the superman.

Given: M = 75000 kg, U = 35 m/s, m = 115 kg.

u = -(75000×35/115)

u = -22826.09 m/s

Note: The velocity is negative because the direction of the superman is opposite the direction of the train.

Hence the superman have to fly 22826.09 m/s in the opposite direction