SSC JE Mechanical Engineering 2017 Set 4 Solved Paper

Assume ‘T’ tension in string Ra (Reaction at ball ‘a’), Rb = reaction at ball ‘b’
All forces resolve in inclined plane in its perpendicular direction →.All forces in inclined direction should be in Equilibriums → ∑Fy = 0 (But inclined plane)
w cos 60° = T cos (90° – a)
∴ 2w sin 30° = T cos α .... (1)
w cos 60° = T sin α ......(2)
Dividing (2) by (1)
⇒

T‌sin‌α

T‌cos‌α

=

w‌cos‌60°

2w‌sin‌30°

⇒tan‌α=

√3

2

⇒tan−1(

√3

2

)=α