A body is in equilibrium under the influence of a
Number of force.Each force has a different line
of action.The minimum number of force required
is
A)2,if their lines of action pass through the centre
    of mass of the body.
B)3,if their lines of action are not parallel.
C)3,if their lines of action are parallel.
D)4,if their lines of action are parallel and all the
    force have the same magnitude.

Asked by Sunil Soni | 18th Aug, 2015, 11:25: PM

Expert Answer:

The body is in equilibrium.
 
A) If the line of action passes through the centre of mass and if only two forces act, then to be in equilibrium the forces need to be equal and opposite in direction.
This is not possible as it is mentioned their line of action is different.
 
B) and C) Three forces which are either parallel or not parallel can make the body in equilibrium as their line of action is different. So, they can add up or subtract to make the body in equilibrium. 
 
D) Four forces can make the body in equilibrium if their magnitudes are equal and their direction is such that they cancel each other. In this case also their line of action is different.
 
Hence, options B, C and D are correct.

Answered by Romal Bhansali | 19th Aug, 2015, 12:37: PM