Section 2: What Is a Machine?
vocabulary
1) Machine: a device that helps do work by either overcoming a force or changing the direction of the force applied
2) Work Input: the work done on a machine; the product of the input force and the distance through which the force is exerted
3) Work Output: the work done by a machine; the product of the output force and the distance through which the force is exerted
4) Mechanical Advantage: a number that tells how many times a machine multiplies force
5) Mechanical Efficiency: a quantity. usually expressed as a percentage that measures the ratio of work output to work input; it can be calculated by dividing work output by work input
2) Work Input: the work done on a machine; the product of the input force and the distance through which the force is exerted
3) Work Output: the work done by a machine; the product of the output force and the distance through which the force is exerted
4) Mechanical Advantage: a number that tells how many times a machine multiplies force
5) Mechanical Efficiency: a quantity. usually expressed as a percentage that measures the ratio of work output to work input; it can be calculated by dividing work output by work input
summary
This section discussed machines. A machine (vocabulary word 1) is a device that makes work easier by changing the size or direction of a force. Machines help you do work that may be harder or more tedious without the machine. When using a machine the you do on a machine is called the work input (vocabulary word 2). You apply a force called the input force to the machine from a distance. The work done by the machine on an object is called work output (vocabulary word 3). The machine applies a force called the output force, through a distance. Machines allow force to be applied over a greater distance, which means that less force will be needed for the same amount of work. Machines make work easier by changing the size or direction (or both) of the input force. So when a machine changes the size of a force, the distance through which the force is exerted must also change. When the size of the force is increased, the distance is decreased (and vice-versa), but both cannot increase.For example, using a ramp as opposed to lifting a box to put it in a car decreases the force applied but increases the distance.
Next is mechanical advantage. Mechanical advantage (vocabulary work 4) is the number of times the machine multiplies force. Mechanical advantage can be calculated with the following equation, mechanical advantage (MA)= output force/input force. A machine that has a mechanical advantage that is greater than 1 can help move or lift heavy objects because the output force is greater than the input force, but a machine with a mechanical advantage that is less than 1 will reduce the output force but can increase the distance an object moves.
Lastly is mechanical efficiency. Mechanical efficiency (vocabulary word 5) is a comparison of a machines's work output with work input. Mechanical efficiency can be measured with the following equation, mechanical efficiency =work output/work input x 100. This tells you what percentage of the work input gets converted into work output, but the mechanical efficiency can never be 100% because the machine always has to use some of its energy to overcome friction. If there are any parts in a machine (which there always is) then there will always be friction that needs to be overcome for the machine to process.
Next is mechanical advantage. Mechanical advantage (vocabulary work 4) is the number of times the machine multiplies force. Mechanical advantage can be calculated with the following equation, mechanical advantage (MA)= output force/input force. A machine that has a mechanical advantage that is greater than 1 can help move or lift heavy objects because the output force is greater than the input force, but a machine with a mechanical advantage that is less than 1 will reduce the output force but can increase the distance an object moves.
Lastly is mechanical efficiency. Mechanical efficiency (vocabulary word 5) is a comparison of a machines's work output with work input. Mechanical efficiency can be measured with the following equation, mechanical efficiency =work output/work input x 100. This tells you what percentage of the work input gets converted into work output, but the mechanical efficiency can never be 100% because the machine always has to use some of its energy to overcome friction. If there are any parts in a machine (which there always is) then there will always be friction that needs to be overcome for the machine to process.