Question

The initial position of an object at rest is given by `3 hati - 8 hatj`. It moves with constant acceleration and reaches to the position `2 hati +4hatj` after 4s. What is its acceleration ?
A. `-(1)/(8) hati + (3)/(2) hatj`
B. `2 hati - (1)/(8) hatj`
C. `-(1)/(2) hati + 8 hatj`
D. `8 hati -(3)/(2) hatj`

Answer 1

Correct Answer - A
Initial position vector, `r_(1) = 3hati - 8hatj`
Final position vector, `r_(2) = 2hati + 4 hatj`
Change in position
`Deltar = r_(2) - r_(1) = 2hati + 4hatj - 3hati +8 hatj =- hatt I +12 hatj`
Using `s = u_(0)t +(1)/(2) a t^(2)`
`rArr -hati +12 hatj = 0 +(1)/(2) a(4)^(2) rArr a = (-hati +12 hatj)/(8) = (-hati)/(8) +(3)/(2) hatj`