Elastic Collisions
Key Questions

billiard balls
Newton's cradle
curling rocks
shuffleboard pucks
bowling ball and pinsAlways take time to think because in reallife situations, most collisions are a combination of elastic and inelastic.

#m_1, m_2# be the two bodies
#u_1, v_1# be initial and final velocities of#m_1#
#u_2,v_2# be initial and final velocities of#m_2# let the initial velocity of
#m_2# = o. So,#u_2# = 0.As the collision is elastic, Kinetic Energy and Momentum are conserved.
Initial Momentum is
#m_1u_1#
Final Momentum is#m_1v_1+m_2v_2# So,
#m_1u_1 = m_1v_1+m_2v_2#
#rArr# #m_1u_1m_1v_1=m_2v_2#
#rArr# #m_1(u_1v_1)=m_2v_2# #># Equation'1'Initial Kinetic Energy is
#1/2m_1u_1^2#
Final Kinetic Energy is#1/2m_1v_1^2+1/2m_2v_2^2# So,
#1/2m_1u_1^2 = 1/2m_1v_1^2+1/2m_2v_2^2#
#rArr# #m_1u_1^2 = m_1v_1^2+m_2v_2^2#
#rArr# #m_1u_1^2m_1v_1^2 = m_2v_2^2#
#rArr# #m_1(u_1^2v_1^2) = m_2v_2^2#
#rArr# #m_1(u_1v_1)(u_1+v_1) = m_2v_2^2# From Equation '1',
#m_1(u_1v_1)=m_2v_2# #rArr# #m_2v_2(u_1+v_1)=m_2v_2^2#
#rArr# #u_1+v_1=v_2# Now,
#v_2=u_1+v_1# From Equation '1',
#m_1(u_1v_1)=m_2v_2# So,
#m_1(u_1v_1)=m_2(u_1+v_1)#
#rArr# #m_1u_1m_1v_1=m_2u_1+m_2v_1#
#rArr# #v_1= (u_1(m_1m_2))/(m_1+m_2)# now, solve the equation '1' using
#v_1=v_2u_1# to get#v_2# I think,
#v_2=(2m_1u_2)/(m_1+m_2)# Final momentum of of
#m_1# is#m_1v_1# and Final momentum of#m_2# is#m_2v_2# :D
PS : Sorry if the math is clumsy, I'm new here.

Answer:
Elastic collision is the collision where there occurs no loss in net kinetic energy as the result of collision.
Explanation:
Total Kinetic energy before the collision= Total kinetic energy after the collision
For example,
Bouncing back of a ball from the floor is an example of elastic collision.
Some other examples are:
#=># collision between atoms
#=># collision of billiard balls
#=># balls in the Newton's cradle... etc.