Mechanical Advantage
How much does an inclined plane, screw, wedge, pulley
or lever really help you?
• Designers of physical systems know from experience that there are many ways to perform the same task
• There job is to find the MOST efficient
• They are looking to find the tool that converts a small input into a much larger output.
•Mechanical Advantage (MA): the ratio of output force to input force of a given machine
• MA has NO units – it is just a comparison/ratio
• When input and output forces are the same, the MA is 1.
• When a machine has an MA GREATER than 1, this generally means it will make tasks easier and faster to accomplish.
• Question: is it possible to have a mechanical advantage LESS than one???
• Is there ever a time when the input force is GREATER than the output force….and we designed it that way?!
Our fist look at scientific formulas!
• Levers:MA = effort arm length
load arm length
• Pulleys:MA = input distance output distance
Let’s try one together…
1. A wheelbarrow has an effort arm 120 cm long and a load arm 40 cm long. What is the mechanical advantage?
Check your learning!1. Find the mechanical advantage of a
wheelbarrow with an effort arm that is 1.8 m long and a load arm that is 0.50 m long.
2. To lift a load 5 cm with a pulley system, 15 cm of string has to be pulled. What is the MA?
3. What is the mechanical advantage of a pulley system if 4 m of string had to be pulled to lift a load a height of 1 m?
Top Related