Question

Two bodies having masses 20kg and 10kg are moving with uniform velocities 20m/sec and 10m/sec from opposite direction and make elastic collision. find the final velocities of two bodies.

Answer 1

8m/sec and 2m/sec

Answer 2

Please give me the solution

Answer 3

initial x momentum = 20*20-10*10 =+300
initial Ke=.5*20*400 +.5*10*100=4500

final speeds in x direction are u and v
so
20 u + 10 v = +300 so v=(30-2u)

.5(20)(u^2) + .5(10)(v^2) = +4500
so
10u^2 +5(900-120u+4u^2) = 4500
u^2 + 450 - 60 u + 2 u^2 = 450
3 u^2 -60 u = 0
u = 0 then v = +30

or the initial case (trivial)
or u = 20
then v = - 10

so I think 0 and +30