Home
Class 12
PHYSICS
A force vec(F)=5 hat(i)+2hat(j)-5hat(k) ...

A force `vec(F)=5 hat(i)+2hat(j)-5hat(k)` acts on a particle whose position vector is `vec(r)=hat(i)-2hat(j)+hat(k)`. What is the torque about the origin ?

A

`8hati+10hatj+12hatk`

B

`8hati+10hatj-12hatk`

C

`8hati-10hatj-8hatk`

D

`10hati-10hatj-hatk`

Text Solution

Verified by Experts

The correct Answer is:
A
`vectau=vecrxxvecF=(hati-2hatj+hatk)xx(5hati+2hatj-5hatk)`
`=|(hati,hatj,hatk),(1,-2,1),(5,2,-5)|=hati(10-2)-hatj(-5-5)+hatk(2+10)`
`vectau=8hati+10hatj+12hatk`
Promotional Banner

Topper's Solved these Questions

  • ROTATIONAL MOTION

    MODERN PUBLICATION|Exercise LEVEL-III (MCQ)|10 Videos

  • RAY OPTICS

    MODERN PUBLICATION|Exercise RECENT COMPETITIVE QUESTION|32 Videos

  • SOLIDS & SEMICONDUCTOR DEVICES

    MODERN PUBLICATION|Exercise Revision Test|28 Videos

Similar Questions

Explore conceptually related problems

Find the magnitude of the vector vec(a) = 3hat(i) +2hat(j) + 6hat(k) .

Find the unit vector in the direction of vector vec(a)=2hat(i)+3hat(j)+hat(k)

Find a unit vector in the direction of vec(A) = 3hat(i) - 2hat(j) + 6hat(k) .

Obtain the projection of the vector vec(a) = 2hat(i) + 3hat(j) + 2hat(k) on the vector vec(b) = hat(i) + 2hat(j) + hat(k) .

The scalar product of the vector vec(a) = hat(i) + hat(j) + hat(k) with a unit vector along the sum of vectors vec(b) = 2hat(i) + 4hat(j) - 5hat(k) and vec(c ) = lambda hat(i) + 2hat(j) + 3hat(k) is equal to one. Find the value of lambda and hence find the unit vector along vec(b) + vec(c ) .

Write the value of cosine of the angle which the vector vec(a) = hat(i) + hat(j) + hat(k) makes with y-axis.