A semicircular disc rests on a horizontal surface with its top flat surface horizontal and circular portion touching down. The coefficient of friction between semi circular disc and horizontal surface is µ. This disc is to be pulled by a horizontal force applied at one edge and it always remains horizontal. When the disc is about to start moving, its top horizontal force will

The resultant of two equal forces P making an angle $$\theta ,$$ is given by

A. $$2{\text{P}}\sin \frac{\theta }{2}$$

B. $$2{\text{P}}\cos \frac{\theta }{2}$$

C. $$2{\text{P}}\tan \frac{\theta }{2}$$

D. $$2{\text{P}}\cot \frac{\theta }{2}$$

A framed structure is perfect, if the number of members are __________ (2j - 3), where j is the number of joints.

A. Equal to

B. Less than

C. Greater than

D. None of these

If a number of forces are acting at a point, their resultant is given by

A. $${\left( {\sum {\text{V}} } \right)^2} + {\left( {\sum {\text{H}} } \right)^2}$$

B. $$\sqrt {{{\left( {\sum {\text{V}} } \right)}^2} + {{\left( {\sum {\text{H}} } \right)}^2}} $$

C. $${\left( {\sum {\text{V}} } \right)^2} + {\left( {\sum {\text{H}} } \right)^2} + 2\left( {\sum {\text{V}} } \right)\left( {\sum {\text{H}} } \right)$$

D. $$\sqrt {{{\left( {\sum {\text{V}} } \right)}^2} + {{\left( {\sum {\text{H}} } \right)}^2} + 2\left( {\sum {\text{V}} } \right)\left( {\sum {\text{H}} } \right)} $$

The linear acceleration (a) of a body rotating along a circular path of radius (r) with an angular acceleration of $$\alpha $$ rad/s², is

A. $${\text{a}} = \frac{\alpha }{{\text{r}}}$$

B. $${\text{a}} = \alpha {\text{r}}$$

C. $${\text{a}} = \frac{{\text{r}}}{\alpha }$$

D. None of these