1.

A particle moves `21m` along the vector `6hat(i)+2hat(j)+3hat(k)` , then `14 m` along the vector `3hat(i)-2hat(j)+6hat(k)`. Its total displacement (in meters) isA. `15hat(i)+2hat(j)+12hat(k)`B. `9hat(i)+12hat(k)`C. `9hat(i)+6hat(j)`D. `24hat(i)+2hat(j)+21hat(k)`

Answer» Correct Answer - D
Total displacement
`=21((6hat(i)+2hat(j)+3hat(k))/(7))+14((3hat(i)-2hat(j)+6hat(k))/(7))`
`=18hat(i)+6hat(j)+9hat(k)+6hat(i)-4hat(j)+12hat(k)`
`=(24hat(i)+2hat(j)+21hat(k))m`


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