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. ` 1 m//s^2`
B. ` 7 m//s^2`
C. ` sqrt 7 m//s^2`
D. `5 m//s^@`

Answer

B

Explanation

Velocity towaeds East,` vec v_1 = 30 hat I m//s`
Velocity towaeds Noth, ` vec v_2 = 40 hat j m//s`
Change in velocity,
` Delta vec v= vec r- vec v-1 = ( 40 hat j - 30 hat i)`
` |Delta vec v|= | 40 hat j - 30 aht i| = sqrt ( 40^2 + (- 30)^2) = 50 m//s`
Average acceleration ,
` a_(av) = (| Delta vec v|/(Deltat) = ( 50 m//s)/( 10 s) = 5 m//s^2`.