Question

During a collision between two objects, the kinetic energy is conserved. Which statement best describes the momentum after the collision?

• A. The momentum equals the kinetic energy
• B. The momentum may be conserved
• C. The momentum must be conserved
• D. The momentum decreases by half
• E. The momentum increases to double the original value

Answer 1

Answer: (C)

The momentum must be conserved

In any collision (either elastic or inelastic ) momentum is always conserved due to momentum conservation law . The given collision is elastic , in which momentum must be conserved.

Momentum is not equal to kinetic energy after collision because ,

total kinetic energy $K=1/2m_1{v}_1^2+1/2m_2{v}_2^2$ and total momentum $p=m_1{v}_1+m_2{v}_2$