Question

A 8700-kgkg boxcar traveling at 14 m/sm/s strikes a second boxcar at rest. The two stick together and move off with a speed of 5.0 m/sm/s.What is the mass of thesecond car?

Answer 1

15000 kg

Step-by-step explanation:

m1v1+m2v2=(m1m2)Vf

8700(15)=(8700+m)5.5

130500=8700+m(5.5)

130500/5.5=8700+m

130500-8700=m

m=15027.3 kg

Answer 2

m₂ = 15660 kg

Step-by-step explanation:

Given that,

Before collision,

Mass of box car 1, m₁ = 8700 kg

Speed of box car 1, u₁ = 14 m/s

Speed of box car 2, u₂ = 0 (at rest)

After collision,

The two stick together and move off with a speed of 5 m/s

Let m₂ is the mass of the second car. As cars stick together, it is a case of inelastic collision. Using the conservation of momentum as follows :

`m_1u_1+m_2u_2=(m_1+m_2)V\\\\8700* 14+0=(8700+m_2)5\\\\121800=43500+5m_2\\\\121800-43500=5m_2\\\\m_2=(78300)/(5)\\\\m_2=15660\ kg`

So, the mass of the second car is 15660 kg.