A body of mass 2 kg makes an elastic collision with another body at rest and contiues to move in the original direction with a speed equal to one thrid of its original speed. Find the mass of the second body.

Explanation

Here, `m_(1)=2kg, u_(1)=upsilon,m_(2)=? u_(2)=0,`
`upsilon_(1)=upsilon//2`
As `upsilon_(1)=((m_(1)-m_(2))u_(1)+2m_(2)u_(2))/((m_(1)+m_(2)))`
`:. (upsilon)/(2)=((2-m_(2))upsilon+2m_(2)xx0)/(2+m_(2))`
or `2+m_(2)=2(2-m_(2))=4-2m_(2)`
`3m_(2)=4-2=2`
`m_(2)=(2)/(3)=0.67kg`