Find the torque about the origin when a force of 3 hatj N acts on a particle whose position vector is 2 hat k m .

Question

Find the torque about the origin when a force of 3 hatj N acts on a particle whose position vector is 2 hat k m . (A) 6 hati Nm  (B) 6 hatj Nm  (C) -6 hati Nm  (D) 6 hatk Nm

Tardigrade Admin · Accepted Answer

Given: vecF=3 hatj N, vecr=2 hatk We know, vecτ= vecr× vecF=2 hatk×3 hatj =6( hatk × hatj)=6(- hati) vecτ=-6 hati Nm

Q. Find the torque about the origin when a force of $3 \hat{j} N$ acts on a particle whose position vector is $2 \hat{k} m$ .

$6 \hat{i} N m$

$6 \hat{j} N m$

$- 6 \hat{i} N m$

$6 \hat{k} N m$

Given: $F = 3 \hat{j} N$ ,
$r = 2 \hat{k}$
We know, $τ = r \times F = 2 \hat{k} \times 3 \hat{j}$
$= 6 (\hat{k} \times \hat{j}) = 6 (- \hat{i})$
$τ = - 6 \hat{i} N m$

Q. Find the torque about the origin when a force of 3j^​N acts on a particle whose position vector is 2k^m .

6i^Nm

6j^​Nm

−6i^Nm

6k^Nm