A body is moving with velocity `30 m//s` towards east. After `10 s` its velocity becomes `40 m//s` towards north. The average acceleration of the body is.

Options

A. `7 m//s^2`
B. `sqrt(7) m//s^2`
C. `5 m//s^(2)`
D. `1 m//s^(2)`

Answer

C

Explanation

Average acceleration = `("Change in velocity")/("Total time")`
`vec(v_L) = 30 hat i m//and vec(v_i) = 40 hat j m//s`
`Delta vec v = vec(v_f) - vec(v_i) = 40 hat j - 30 hat i m//s`
`|Delta vecv|sqrt(30^2 + 40^2) =sqrt(900 + 1600) = 50 m//s`
`vec a= (|vec(_V_f) -vec(V_i)|)/(Delta t) = (sqrt(50))/(10) = 50 ms^-2`.