Question 463: Centre of Mass and Rotational Motion

Question

A force $$\overrightarrow F $$ = $${4\widehat i + 3\widehat j + 4\widehat k}$$ is applied on an intersection point of x = 2 plane and x-axis. The magnitude of torque of this force about a point (2, 3, 4) is ___________. (Round off to the Nearest Integer)

Accepted Answer

$$\overrightarrow 	au   = \overrightarrow r  	imes \overrightarrow F $$
$$ = \left[ {(2 - 2)\widehat i + (0 - 3)\widehat j + (0 - 4)\widehat k} ight] 	imes (4\widehat i + 3\widehat j + 4\widehat k)$$
$$ = ( - 3\widehat j - 4\widehat k) 	imes (4\widehat i + 3\widehat j + 4\widehat k)$$
$$ =  - 16\widehat j + 12\widehat k$$
$$|\overrightarrow 	au  |\, = 20$$ units

Centre of Mass and Rotational Motion

A force $\overrightarrow F = {4\widehat i + 3\widehat j + 4\widehat k}$ is applied on an intersection point of x = 2 plane and x-axis. The magnitude of torque of this force about a point (2, 3, 4) is ___________. (Round off to the Nearest Integer)

Choose the correct answer: