The velocity of a bullet is reduce from `200 m//s` to `100m//s` while travelling through a wodden block of thickness `10 cm` Assuming it to be uniform, the retardation will be

Options

A. `15xx10^(4)m//s^(2)`
B. `10xx10^(4)m//s^(2)`
C. `12xx10^(4)m//s^(2)`
D. `14.5m//s^(2)`

Answer

A

Explanation

From equation of motion
`V^(2)+u^(2)+2as`…(1)
Where `v` is final velociy, `u` is initial velocity `a` is retardation and `s` is distance travel.
Given, `v= 100 m//s, u= 200 m//s`
`s=10 cm= 10xx10^(-2)`
Putting the numerical values in Eq.(1), we have
`:. (100)^(2)= (200)^(2)+2xx1xx10xx10^(-2)`
`implies 30000= 2axx10^(-2)`
`implies a=(30000)/(20xx10^(-2))`
`= -15xx10^(4)m//s^(2)`
Minus sign shows negatice acceleration i.e., retardation.