At a given instant of time two particles are having the position vectors `4 hati -4hatj + 7 hatk` metre and `2 hat i +2 hatj + 5hatk` respectively. If the velocity of the first particle be `0.4 hati ms^-1`, the velocity of second particle in metre per second if they collide after 10 s is

Options

A. `6(hati -hatj+1/3 hatk)`
B. `0.6(hati -hatj+1/3 hatk)`
C. `6(hati +hatj+1/3 hatk)`
D. `0.6(hati +hatj-1/3 hatk)`

Explanation

Comparing ,`x=6t` with `x=(ucostheta)` and `y=8t-5t^2` with `y=(usintheta)t-1/2g t^2` then,
`impliesucostheta=6,u=sintheta=8`
The expression for range Ris given as,
`R=(u^2sin2theta)/g`
`impliesR=u^2((2sinthetacostheta))/(g)`
`R=(2xx6xx10)/10`
`:.R=9.6m`