What is the relationship between the mechanical advantage and the velocity ratio for:(a) an idealmachine(b) apracticalmachine?

(a) For an ideal machine, the mechanical advantage is equal to the velocity ratio. This is because there are no energy losses due to friction or other inefficiencies.

Step by step:

1. The mechanical advantage of a machine is the ratio of the output force (the force exerted by the machine) to the input force (the force applied to the machine).
2. The velocity ratio of a machine is the ratio of the distance moved by the effort (input) to the distance moved by the load (output).
3. In an ideal machine, all the input energy is converted into output energy without any losses. Therefore, the mechanical advantage equals the velocity ratio.

(b) For a practical machine, the mechanical advantage is less than the velocity ratio. This is due to energy losses in the machine, mainly due to friction.

Step by step:

1. In a practical machine, not all the input energy is converted into output energy. Some energy is lost, mainly due to friction.
2. This means that the output force (or distance moved by the load) is less than what it would be in an ideal machine.
3. Therefore, the mechanical advantage (output force/input force) is less than the velocity ratio (distance moved by effort/distance moved by load).