Question 495: Centre of Mass and Rotational Motion

Question

If force $\vec{F}=-3 \hat{i}+\hat{j}+5 \hat{k}$ acts along $\vec{r}=7 \hat{i}+3 \hat{j}+\hat{k}$ then the torque acting at that point is

Accepted Answer

$$ \begin{aligned} \vec{	au}=\vec{r} 	imes \vec{F} & =\left|\begin{array}{ccc} \hat{i} & \hat{j} & \hat{k} \ 7 & 3 & 1 \ -3 & 1 & 5 \end{array}ight| \ & =\hat{i}(15-1)-\hat{j}(35+3)+\hat{k}(7+9) \ & =(14 \hat{i}-38 \hat{j}+16 \hat{k}) \mathrm{N}-\mathrm{m} \end{aligned} $$

Answer

$(14 \hat{\mathrm{i}}-38 \hat{\mathrm{j}}+16 \hat{\mathrm{k}})$

Answer

$(-14 \hat{i}+34 \hat{j}-16 \hat{k})$

Answer

$(21 \hat{\mathrm{i}}+4 \hat{\mathrm{j}}+4 \hat{\mathrm{k}})$

Answer

$(4 \hat{\mathrm{i}}+4 \hat{\mathrm{j}}+6 \hat{\mathrm{k}})$

Centre of Mass and Rotational Motion

If force \vec{F}=-3 \hat{i}+\hat{j}+5 \hat{k} acts along \vec{r}=7 \hat{i}+3 \hat{j}+\hat{k} then the torque acting at that point is

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