Simple Screw Jack: Understanding Velocity Ratio

What is the formula to calculate the velocity ratio of a simple screw jack?

Choose the correct formula from the following options:

a) velocity ratio = pitch of the screw / length of effort wheel

b) velocity ratio = length of effort wheel / pitch of the screw

c) velocity ratio = length of effort wheel * pitch of the screw

Answer:

The correct formula to calculate the velocity ratio of a simple screw jack is option b) velocity ratio = length of effort wheel / pitch of the screw.

Explanation: The velocity ratio of a simple screw jack is an important factor to consider in understanding its efficiency. The velocity ratio is calculated by dividing the length of the effort wheel by the pitch of the screw.

For example, if the length of the effort wheel is 10 cm and the pitch of the screw is 2 cm, the velocity ratio would be 5. This means that for every 5 rotations of the effort wheel, the load will move 1 rotation.

Understanding the velocity ratio of a simple screw jack is crucial in determining the mechanical advantage it provides and how much effort is required to lift a load using the jack. It helps in designing and using screw jacks effectively in various applications.