A body A of mass 2.0kg makes an elastic collision with another body B at rest. After collision,A continues to move in the original direction but with one-fourth of its original speed. Determine the value of mass B

Answer 1

call original speed v

Original momentum = 2 v
Final momentum = 2 v/4 + Mb Vb
so
4 v = v + 2 Mb Vb
or
Mb Vb = 3 v

original Ke = .5 (2) v^2 = v^2
final Ke = .5 (2)v^2/16 + .5 Mb Vb^2
so
(15/16) v^2 = (1/2) Mb Vb^2
(15/8) v^2 = Mb Vb^2 = 3 v Vb
(5/8)v = Vb
but
Mb Vb = 3 v so Vb = 3 v/Mb
3 v/Mb = (5/8)v
3/Mb = 5/8
Mb = 24/5

Answer 2

Terrible explanation...not exactly sure how (4v) = v + 2(Mb*Vb) is simplified to 3v = Mb*Vb....did the 2 get lost somewhere or..?

Answer 3

wrong