Engineering Mechanics

Engineering Mechanics
Question:-
Option (A)
5 N
Option (B)
20 N
Option (C)
25 N
Option (D)
¥
Correct Option:
D
Question Solution:
By Lami’s theorem If P , Q and R the three vectors acting at a point, and their resultant is zero (i.e. the system is in equilibrium)

Then (P/sina) = (Q/sinb) = (R/sing)
To completely straighten the rope
g = 180° and a = b = 90°
\ P = Q = R (sin 90°/sin 180°) = (1 x 10) x (1/0) = ¥
Question:-
Option (A)
24 N
Option (B)
30 N
Option (C)
42 N
Option (D)
50 N
Correct Option:
D
Question Solution:
AC = BC = 1 m;
CD = Ö(12-(0.8)2) = 0.6m
Sin a = 0.8 and cos a = 0.6

Since there forces W,T and T are in equilibrium,
\ (W/sin2a) = (T/sin(180-a))
(W/2sina cosa) = (T/sina)
\ T = (W/2 cosa) = (60/2 x 0.6)) = 50 N
Question:-
Option (A)
78 N
Option (B)
86 N
Option (C)
99 N
Option (D)
98 N
Correct Option:
A
Question Solution:
From the geometry of the system

(W/sin 75°) = (T2/sin 150°)
T2 = W (sin 150°/sin 75°)
= ((150 x 0.5) /0.966) ~ 78 N
Question:-
Option (A)
zero
Option (B)
2Ö2P
Option (C)
2P
Option (D)
Ö5P
Correct Option:
B
Question Solution:
Resultant force in horizontal direction = (3P-P)
2P towards left

Resultant force in vertical direction
= (4P-2P)= 2P downwards
Overall resultant force =
Question:-
Option (A)
22 m/sec
Option (B)
1 m/sec
Option (C)
Ö21 m/sec
Option (D)
11 m/sec
Correct Option:
D
Question Solution:
Velocity = mass x acceleration
Or 50 = 10 x a
Or a = 5 m/sec2
Velocity after 2 second, u = u + at = 1 + 5 x 2 = 11 m/sec
Question:-
Option (A)
(M + m)F/m
Option (B)
MF/m
Option (C)
mF/M
Option (D)
mF/(M+m)
Correct Option:
D
Question Solution:
From free body diagram
F-N = Ma ..... (i)
Or N = ma .....(ii)
From equations (i)and (ii) we get
N = mF/(m+M)