home > Sample Assignment > Physics Homework Assignment > Loss in Kinetic Energy

Loss in Kinetic Energy Sample Assignment

Question: A railway wagon of mass 20 tonnes, moving at 3 m/s, collides with a second wagon of mass 15 tonnes which is stationary. The coefficient of restitution if 0.6. Find the loss of kinetic energy during the impact.

Ans:  The loss in kinetic energy is calculated as:

m₁ = 20 000 kg
u₁= 3 m/s
m₂ = 15 000 kg
u₂ = 0
e = 0.6
20000 × 3 + 0 = 20000 v₁ + 15000 v₂
60 = 20v₁ + 15v₂
0.6 = -(v₁ - v₂)/3
-1.8 = v₁ - v₂
-36.36 = 20v₁ - 20v₂
96.36 = 35 v₂
v₂ = 2.753 m/s
v₁ = 0.952 m/s
Ke = 0.5 × 20000 × 0.9522 + 0.5 × 15000× 2.7532 = 65905 J
Ke before = 0.5 × 20000 × 32 = 90000 J
Loss in Ke = 24095 J

Other Sample Assignments in Physics Homework Assignment :

Work Energy Power	Minimum Pulling Force
Shear Stress	Loss in Kinetic Energy
Impulse

---

---