In a closed system, an object with a mass of 1.5 kg collides with a second object. The two objects then move together at a velocity of 50 m/s . The total momentum of the system is 250 kg⋅m/s . What is the mass of the second object?
Let the mass of the second object be "m" kg.
According to the law of conservation of momentum, the total momentum before the collision is equal to the total momentum after the collision.
The momentum of the first object before the collision is given by: 1.5 kg * 0 m/s = 0 kg⋅m/s.
Therefore, the momentum of the second object before the collision is equal to the total momentum of the system: 250 kg⋅m/s - 0 kg⋅m/s = 250 kg⋅m/s.
The momentum of an object is given by the mass of the object multiplied by its velocity: m kg * 50 m/s = 250 kg⋅m/s.
Therefore, the mass "m" of the second object is: 250 kg⋅m/s / 50 m/s = 5 kg.
Thus, the mass of the second object is 5 kg. Answer: \boxed{5}.