Name a machine for each of the following use :
(a) to multiply the force,
(b) to change the point of application of force,
(c) to change the direction of force,
(d) to obtain the gain in speed.
Pick out the one from the options which is responsible for changing the point of application of force.
Name a machine which is used to change the direction of the force.
Name the force which is responsible for change in position or state of an object