Home Page | Input vs. Output Forces | Mechanical Advantage | Ideal Mechanical Advantage | Mechanical Efficiency | Practice Questions | Challenge Questions | Interactive Quiz | Bibliography Note: This page is not for marking. My assigned topic is mechanical advantage. A machine's mechanical efficiency is the useful work the machine produces compared to the work needed to operate it. The useful work output is the work the machine is designed to perform. In an ideal world with no friction, the work output and the work input are equal to each other, however in the real world, some of the output work is done by friction making the useful output work always less than the input work. To calculate work (W), the force (F) in Newtons is multiplied by the distance (d) moved in metres to create the formula W = F x d. The metric unit for measuring work is the Joule (J). To calculate the force a mass exerts, you multiply the mass in kilograms by 9.8. To calculate the mechanical efficiency of a machine, the output work (Wo) is divided by the input work (Wi) and multiplied by 100 to get a percentage. This creates the formula (Wo/Wi) x 100%. Example: An 200N box is moved up a 4 metre long ramp. If the person pushes with a force of 150N to raise the box 2 metres, the ME is 67% (rounded to the nearest whole number).
Wo = F x d Wo = 200N x 2 m Wo = 400J
Wi = F x d Wi = 150N x 4 m Wi = 600J
ME = (Wo/Wi) x 100% ME = (400J/600J) x 100% ME = 0.67 x 100% ME = 67% The efficiency of any machine is always less than 100% because some of the input work is used to compensate for the work done by friction. To increase the efficiency of a machine, you need to decrease the frictional force. The best way to do so is by adding a lubricant such as grease or oil to any surfaces that rub together. The efficiency of some machines would not increase by adding a lubricant. Adding a lubricant to an incandescent light bulb would not increase the efficiency. Here are the efficiencies of common mechanisms:
Home Page | Input vs. Output Forces | Mechanical Advantage | Ideal Mechanical Advantage | Mechanical Efficiency | Practice Questions | Challenge Questions | Interactive Quiz | Bibliography
Note: This page is not for marking. My assigned topic is mechanical advantage.
A machine's mechanical efficiency is the useful work the machine produces compared to the work needed to operate it. The useful work output is the work the machine is designed to perform. In an ideal world with no friction, the work output and the work input are equal to each other, however in the real world, some of the output work is done by friction making the useful output work always less than the input work. To calculate work (W), the force (F) in Newtons is multiplied by the distance (d) moved in metres to create the formula W = F x d. The metric unit for measuring work is the Joule (J). To calculate the force a mass exerts, you multiply the mass in kilograms by 9.8. To calculate the mechanical efficiency of a machine, the output work (Wo) is divided by the input work (Wi) and multiplied by 100 to get a percentage. This creates the formula (Wo/Wi) x 100%.
Example: An 200N box is moved up a 4 metre long ramp. If the person pushes with a force of 150N to raise the box 2 metres, the ME is 67% (rounded to the nearest whole number).
Wo = F x d
Wo = 200N x 2 m
Wo = 400J
Wi = F x d
Wi = 150N x 4 m
Wi = 600J
ME = (Wo/Wi) x 100%
ME = (400J/600J) x 100%
ME = 0.67 x 100%
ME = 67%
The efficiency of any machine is always less than 100% because some of the input work is used to compensate for the work done by friction. To increase the efficiency of a machine, you need to decrease the frictional force. The best way to do so is by adding a lubricant such as grease or oil to any surfaces that rub together. The efficiency of some machines would not increase by adding a lubricant. Adding a lubricant to an incandescent light bulb would not increase the efficiency.
Here are the efficiencies of common mechanisms:
Home Page | Input vs. Output Forces | Mechanical Advantage | Ideal Mechanical Advantage | Mechanical Efficiency | Practice Questions | Challenge Questions | Interactive Quiz | Bibliography