Question

You will find the size and field of action of the resultant of two parallel forces with sizes 40N and 60N, whose impactors are at a distance of 2m. The forces act: a, In the same direction b. In the opposite direction

Answer 1

The resultant of the system if the forces are in the same direction

$R=\sum F = 40 N+ 60N=100N$

Assume distance d from one end of the system say point A

$\sum M_A^F = \sum F \times x$

$\sum M_A^F = 100 \times 2 = 200N.m$

$M_A^R=\sum M_A^F$

$100 d=200 \implies d= 2 m$

Thus R =100 N , 2 m to the right

The resultant of the system if the forces are in a different direction

$R=\sum F = -40 N+ 60N=20N$

Assume distance d from one end of the system say point A

$\sum M_A^F = \sum F \times x$

$\sum M_A^F = 20 \times 2 = 40N.m$

$M_A^R=\sum M_A^F$

$20 d=40 \implies d= 2 m$

Thus R =20 N , 2 m to the right