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. `sqrt7 m//s^(2)`
D. `5 m//s^(2)`

Answer

D

Explanation

(d): `vecv_(1)=30hati`
`vec(v)_(2)=40hatj`

Average acceleration
`|veca|=(|vecv2-vecv1|)/(t)`
`(|40hatj-30hati|)/(10)`
`|vec a|=|4hatj-3hati|=|-3hati+4hatj|`
`|veca|=|sqrt(9+16)|=5 m//s^(2)`