Physics
A body is acted upon by two forces each of magnitude F, but in opposite directions. State the effect of the forces if
(a) both forces act at the same point of the body.
(b) the two forces act at two different points of the body at a separation r.
Answer
(a) As two forces of same magnitude are acting on a body at the same point and they are in opposite direction so the resultant force will be zero.
F – F = 0
(b) When two forces of same magnitude act on a body at two different points at a separation r and in opposite direction then the moment of force will be Fr
Moment of forces = F × r
Related Questions
State the principle of moments. Name one device based on it.
A, B and C are the three forces each of magnitude 4N acting in the plane of paper as shown in figure. The point O lies in the same plane.
(i) Which force has the least moment about O? Give reason.
(ii) Which force has the greatest moment about O? Give reason.
(iii) Name the forces producing (a) clockwise, (b) anticlockwise moments.
(iv) What is the resultant torque about the point O?
Draw a neat labelled diagram to show the direction of two forces acting on a body to produce rotation in it. Also mark the point O about which the rotation takes place.
What do you understand by the term couple? State its effect on a body. Give two examples in our daily life where couple is applied to turn a body.