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Dot product of two vectors overset(rarr)...

Dot product of two vectors `overset(rarr)A` and `overset(rarr)B` is defined as `overset(rarr)A.overset(rarr)B=aB cos phi` , where `phi` is angle between them when they are drawn with tails coinciding. For any two vectors . This means `overset(rarr)A . overset(rarr)B=overset(rarr)B. overset(rarr)A` that . The scalar product obeys the commutative law of multiplication, the order of the two vectors does not matter. The vector product of two vectors `overset(rarr)A` and `overset(rarr)B` also called the cross product, is denoted by `overset(rarr)A xx overset(rarr)B` . As the name suggests, the vector product is itself a vector. `overset(rarr)C=overset(rarr)A xx overset(rarr)B` then `C=AB sin theta` ,
`overset(rarr)A=hat i+ hat j-hatk` and `overset(rarr)B=2 hat i +3 hat j +5 hat k` angle between `overset(rarr)A` and `overset(rarr)B` is

A

`120^(@)`

B

`90^(@)`

C

`60^(@)`

D

`30^(@)`

Text Solution

Verified by Experts

The correct Answer is:
b

`barA.barB=2 +3-5=0 rarr barA bot barb`
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Knowledge Check

  • Dot product of two vectors overset(rarr)A and overset(rarr)B is defined as overset(rarr)A.overset(rarr)B=aB cos phi , where phi is angle between them when they are drawn with tails coinciding. For any two vectors . This means overset(rarr)A . overset(rarr)B=overset(rarr)B. overset(rarr)A that . The scalar product obeys the commutative law of multiplication, the order of the two vectors does not matter. The vector product of two vectors overset(rarr)A and overset(rarr)B also called the cross product, is denoted by overset(rarr)A xx overset(rarr)B . As the name suggests, the vector product is itself a vector. overset(rarr)C=overset(rarr)A xx overset(rarr)B then C=AB sin theta , A force overset(rarr)F=3hat i +c hat j + 2 hatk acting on a particle causes a displacement d=4hat i+ 2 hat i + 3 hat k . If the work done (dot product of force and displacement) is 6J then the value of c is :

    A
    12
    B
    0
    C
    6
    D
    1
  • Dot product of two vectors overset(rarr)A and overset(rarr)B is defined as overset(rarr)A.overset(rarr)B=aB cos phi , where phi is angle between them when they are drawn with tails coinciding. For any two vectors . This means ovsert(rarr)A . overset(rarr)B=overset(rarr)B. overset(rarr)A that . The scalar product obeys the commutative law of multiplication, the order of the two vectors does not matter. The vector product of two vectors overset(rarr)A and overset(rarr)B also called the cross product, is denoted by overset(rarr)A xx overset(rarr)B . As the name suggests, the vector product is itself a vector. overset(rarr)C=overset(rarr)A xx overset(rarr)B then C=AB sin theta , For non zero vectors overset(rarr)A, overset(rarr)B, overset(rarr)C,|(overset(rarr)Axxoverset(rarr)B).overset(rarr)C|=|overset(rarr)A||overset(rarr)B||overset(rarr)C| holds if and only if

    A
    `overset(rarr)A.overset(rarr)B=0,overset(rarr)B.overset(rarr)C=0`
    B
    `overset(rarr)B.overset(rarr)C=0,overset(rarr)C.overset(rarr)A=0`
    C
    `overset(rarr)C.overset(rarr)A=0,overset(rarr)A.overset(rarr)B=0`
    D
    `overset(rarr)A.overset(rarr)B=overset(rarr)B.overset(rarr)C=overset(rarr)C.overset(rarr)A=0`
  • Let overset(rarr)C = overset(rarr)A+overset(rarr)B then :

    A
    `|overset(rarr)C|` is always greater then `|overset(rarr)A|` and `|overset(rarr)C| lt |overset(rarr)B|`
    B
    it is possible to have
    C
    `|overset(rarr)C|` is always equal to `|overset(rarr)A + overset(rarr)B|`
    D
    `|overset(rarr)C|` is never equal to `|overset(rarr)A+overset(rarr)B|`
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