A body is acted upon by two forces, each of magnitude F, but in opposite directions. State the effect of the forces when
(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 d.
Give an example for each of the following uses of a machine:
to change the point of application of force
One joule is the amount of work done when a force of ......... moves a body through a distance of .......