Question

Two like parallel forces $20N$ and $30N$ act at the ends $A$ and $B$ of a rod $1.5m$ long. The resultant of the forces will act at the point:

• A. $90cm$ from A
• B. $75cm$ from B
• C. $20cm$ from B
• D. $85cm$ from A

Answer 1

Answer: (A)

$90cm$ from A

Consider the point at which resultant of the forces will act, is 'x' m from the point A.

Thus the point is (1.5 - x) m far from the point B.

Thus, using the formula Torque = Distance x Force acting

$20x=30(1.5-x)$

or,$2x=4.5-3x$

or,$5x=4.5$

or, $x=0.9mor90cm$

Thus the resultant point will be 0.9 m or 90 cm far from point A