Theory Of Machine - Study Mode

[#376] If two moving elements have surface contact in motion, such pair is known as
Correct Answer

(D) Lower pair

Explanation

Solution: When two elements of a pair have a surface contact when relative motion takes place and the surface of one element slides over the surface of the other, the pair formed is known as lower pair.

[#377] The primary unbalanced force due to inertia of reciprocating parts in a reciprocating engine is given by (where m = Mass of reciprocating parts, $$omega $$ = Angular speed of crank, r = Radius of crank, $$ heta $$ = Angle of inclination of crank with the line of stroke and n = Ratio of the length of connecting rod to radius of crank)
Correct Answer

(B) $${ ext{m}}{omega ^2}{ ext{r}}cos heta $$

[#378] The secondary unbalanced force due to inertia of reciprocating parts in a reciprocating engine is given by (where m = Mass of reciprocating parts, $$omega $$ = Angular speed of crank, r = Radius of crank, $$ heta $$ = Angle of inclination of crank with the line of stroke and n = Ratio of the length of connecting rod to radius of crank)
Correct Answer

(D) $${ ext{m}}{omega ^2}{ ext{r}}frac{{cos2 heta }}{{ ext{n}}}$$

[#379] The velocity of piston in a reciprocating steam engine is given by (where $$omega $$ = Angular velocity of crank, r = Radius of crank pin circle, $$ heta $$ = Angle turned by crank from inner dead center and n = Ratio of length of connecting rod to the radius of crank)
Correct Answer

(A) $$omega { ext{r}}left( {sin heta + frac{{sin 2 heta }}{{ ext{n}}}} ight)$$

[#380] The sensitiveness of the governor __________ as the speed range decreases.
Correct Answer

(C) Increases

Explanation

Solution: For a given lift of the sleeve, the sensitiveness of the governor increases as the speed range decreases.