Simple Machines Mechanical Advantage
Mechanical Advantage Describes how much the device helps you, i. e. how much advantage do you get from using it? Can be expressed as the ratio of: 1) the resistance force (i. e. the load) to the effort force required to move it 2) the distance traveled by the effort force to the distance traveled by the resistance force These calculated ratios allow designers to manipulate a design to change speed, distance, force, and function.
Mechanical Advantage Example A mechanical advantage of 4: 1 tells us what about a mechanism? Magnitude of Force: Effort force is 4 times less than the resistance force. Distance Traveled by Forces: Effort force travels 4 times farther than the resistance force would have. In other words the work is 4 x easier, or you can do 4 x more.
Mechanical Advantage Ratios One is the magic number If MA is greater than 1: less effort force but greater effort distance are required to overcome a given resistance force If MA is less than 1: greater effort force but less effort distance are required to overcome a given resistance force MA is never less than zero.
Ideal Mechanical Advantage (IMA) Theory-based calculation (i. e. design prediction) Used in efficiency and safety factor design calculations Frictional losses are not taken into consideration Ratio of force distances DE = Distance traveled by effort force DR = Distance traveled by resistance force
Actual Mechanical Advantage (AMA) Inquiry-based calculation (i. e. you actually measure it) Used in efficiency calculations Frictional losses are taken into consideration Ratio of force magnitudes FR = Magnitude of resistance force FE = Magnitude of effort force
Real World Mechanical Advantage Can you think of a machine that has a mechanical advantage greater than 1?
Real World Mechanical Advantage Can you think of a machine that has a mechanical advantage less than 1?
Work The force applied on an object times the distance traveled by the object Initial position Final position Force (F) Distance (d) Work = Force * Distance = F*d *The force needed to overcome friction is not considered*
Work The product of the effort times the distance traveled will be the same regardless of the system mechanical advantage
Image Resources Microsoft, Inc. (2008). Clip Art. Retrieved January 10, 2008, from http: //office. microsoft. com/en-us/clipart/default. aspx