A car travelling at 20 km/h speeds up to 6 km/h in 6 seconds. What is its acceleration ?

Options

A. a = 1.85 m/`s^(2)`
B. a = 2 m/`s^(2)`
C. a = 9.8 m/`s^(2)`
D. a = 4.85 m/`s^(2)`

Answer

A

Explanation

Here, Initial speed, `u` = 20 km/h
`" " =(20xx1000" m") /(60xx60" s")`
`" "= 5.55 m//s" "` …(1)
Final speed, `v`= 60 km/h
`" "=(60xx1000" m")/(60xx60" s")`
`" "` = 16.66 m/s `" "`…(2)
Acceleration, `a` = ? (To be calculated)
And, `" "` Time, `t` = 6 s
We know that : `" "v=u+at`
So, `" "` 16.66=5.55+`axx6`
`" "6a= 16.66 - 5.55`
`" " 6a= 11.11`
`" "a=(11.11)/(6)`
Thus, Acceleration, `a` = 1.85 m/`s^(2)`.