Question

A bullet, moving with a speed of `150(m)//(s)`, strikes a wooden plank. After passing through the plank, its speed becomes `125(m)//(s)`. Another bullet of the same mass and size strikes the plank with a speed of `90(m)//(s)`. Its speed after passing through the plank would be
A. `25(m)//(s)`
B. `35(m)//(s)`
C. `50(m)//(s)`
D. `70(m)//(s)`

Answer 1

Correct Answer - B
`(1)/(2)m(150)^2=(1)/(2)m(125)^2+Rd` .(i)
`(1)/(2)m(90)^2=(1)/(2)mv^2+Rd` .(ii)
`(150)^2-(125)^2=(90)^2-v^2`
`v=35(m)//(s)`