The total momentum of a system of masses (i. e. moving bodies) in any one direction remains constant, unless acted upon by an external force in that direction. This statement is called

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