A train starting from a railway station and moving with uniform acceleration attains a speed of `40 km ^(-1)` in 10 minute. Find its acceleration.

Options

A. `1ms ^(-2)`
B. `2ms ^(-2)`
C. `3ms ^(-2)`
D. `4ms ^(-2)`

Answer

B

Explanation

`d = v _(0) t + 1/2 at^(2), d = 16 m, t = 4s`
`16= v _(0) + 8a " "…(1)`
Now, `d = 9m, t =3s`
`9= 3v_(0) + (9a)/(2) therefore 18 = 6v_(0) + 9a " "…(2)`
`therefore 48=12v_(0) + 24 a ` (eq. (i) is multiplied by 3)
`36=12v _(0) + 18 a ` (eq. (ii) is multiplied by 2)
`{:(-,-,-), (12=6a,,),(therefore a = 2ms ^(-2),,):}`